There is already a guide on here that lists the locations, but for those who'd like a little more detail, I found a guide at videogamesblogger.com that could be helpful. I edited it to remove as many spoilers as I felt I could, but Note: there are still a few minor spoilers. I also added some more detail where I felt it was lacking. If you would like to see the original guide or watch a video showing where the keys are, go here: http://www.videogamesblogger.com/2014/02/04/fable-anniv....htm
Edit: Due to a bug, one of the keys can become unobtainable. As a result, I have rearranged the order slightly and added info for the key to help players avoid this.
• Silver Key Location #1: The first time you leave the guild, look for vines to destroy around the center of the map and you will find your first Silver Key.
• Silver Key Location #2: During your first visit to Bowerstone South, enter the first building on your left (the Armor shop) and go upstairs to find this key on the balcony.
• Silver Key Location #3: After you buy a fishing rod, you can go back to the Guild and enter the Guild Woods. There’s only one body of water here that you can fish in (on the right from the entrance), so find the fishing spot and fish out a Silver Key.
• Silver Key Location #4: Your first time entering Greatwood Lake coming from Greatwood Entrance, immediately veer off to the right to obtain this very obvious key.
• Silver Key Location #5: Go to the area where you had the Hobbe Killing Contest with Whisper in Orchard Farm, and fish off of the dock.
• Silver Key Location #6: During your first visit to Fisher Creek, save the fishermen and then fish around the fishing spots behind his house to fish up this key.
• Silver Key Location #7: (New Silver Key introduced in The Lost Chapters) After saving the fisherman from bees during your first visit to Fisher Creek, you can visit him later to take part in a fishing competition. If you get second place, you can get rewarded with a silver key. This becomes easier after you get The Rod of Champions from the fishing competition. This is the low level prize. Check the sign in the area to see the current size to beat.#Note: Unlike the chicken-kicking competition, if you land first prize, you will be given the key as well.
#Note 2: In the comments DAN NUFC let me know of a bug relating to this achievement. If you do not visit Fisher Creek and get the cutscene with the bees attacking the fisherman prior to beating the game, the cutscene may not happen for you. This results in the fisherman not spawning and you having no way of getting this key. At the moment, I don't know at what point in the main quest-line the bug occurs. To be safe, I have brought this key higher on the list so anyone who is using this as a checklist will see this key sooner. My recommendation is to get this one early, or at least make sure to visit the area early on and kill the bees so the fisherman spawns here.
• Silver Key Location #8: Visit Rose Cottage in Greatwood, and dig in the round flowerbed beside the house.
• Silver Key Location #9: Go to the end of Hobbe Cave where you rescued James in the “Hobbe Cave Quest” side quest, and dig in the round mushroom patch to find this key.
• Silver Key Location #10: This key can be found in Darkwook Lake. Just across form Darkwood Bordello there is a tall stone with a hole in it. Shoot an arrow through this hole to get your key.
• Silver Key Location #11: Go to the Ancient Cullis Gate is in Darkwood. You need to fish off the side of the bridge to get it. There is a fishing spot on each side, so check each one (depending on which direction you are heading from).
• Silver Key Location #12: (New Silver Key introduced in The Lost Chapters) You will need to clear Oakvale’s beach of the Pirate Ghost before you can compete in the Chicken Kicking Competition. Once you do, score between 150 and 249 points to get the key.#Note: Getting 250 will get you first prize, not the Silver Key. Even after winning the first prize, you will still not get the key if you get 250 or higher.
• Silver Key Location #13: After helping the Ghost Pirate on the beach in Oakvale, he will tell you where his treasure is buried. If you go the Memorial Garden, dig under your Dad’s grave for the key as well as a weapon. Make sure to dig near the statue.
• Silver Key Location #14: Go to Twinblade’s Camp, not the Elite Camp. Here, you want to dig in the circle of flowers in front of the chest.
• Silver Key Location #15: Head towards the Demon Door at the Grey House, and fish into the water.
• Silver Key Location #16: Upon entering Witchwood Stones, look into the water immediately to the left to find the key.
• Silver Key Location #17: As you move on through Witchwood Lake, look for a red statue to the left of the screen. Dig under the statue to find the key.
• Silver Key Location #18: This key is in between the house that you can purchase in Knothole Glade and the house to the left of it. Go in between the two houses and dig in the circular dirt patch to get this key.
• Silver Key Location #19: Beside the house in Windmill Hill, dig in the patch of dirt to the left of it. Look for another circle to dig in for this key.
• Silver Key Location #20: Still in Windmill Hill, head towards Gibbet Woods, but stop and go towards the windmill. If you go behind the house, you should see a patch of dirt to dig in. Your key is here.
• Silver Key Location #21: If you choose to marry Lady Grey, you can access to the area with this key during your fight with Thunder. When you fall off the cliff, there is a shallow body of water for you to fish in. This is where your key is. If you choose not to pursue Lady Grey's hand in marriage, TedyBearOfDeath let me know of a way to get this key in the comments section.
Here's the comment for you (shortened): "...go to Headman's Hill and stand next to the fence by the treasure chest and fast travel away. Then use the fast travel recall option and it will put you down there." Verified this myself before editing. Thanks for bringing this to my attention TedyBearOfDeath!
• Silver Key Location #22: (This Silver Key is MISSABLE! - see note below) You must get access to Bowerstone Manor by either becoming mayor of Bowerstone North, or by marrying Lady Grey. Once you do, this key is IN the bed (you must examine the bed).#Note: Demon Haze II mentioned in the comments that this is a potentially missable key!
Here's the comment for easy reference: "I just wanted to point out that #21 is also missable if you try to marry the woman who gives you information about Lady Greys presents. She no longer talks to you and the door to the manor remains closed."
• Silver Key Location #23-25: In Lynchfield Graveyard there are 3 keys. The first key is in a tomb at the back of the graveyard that reads "Here lies Scoran Daith. The Necromancer embraces death." You will need to push the top off of the coffin. Exit that tomb and dig in the first grave on your left for the second key. The last key is in the "small stream, in the middle of the graveyard, directly south of the "transporter" on your map." You will likely get these as you complete the quest here as the pieces of armor you seek are buried, in coffins, and in water.
*credit to JustAnothrMaori for reminding me to add the location name for these 3
*Credit to Warboy925 for suggesting the detail I've added in
• Silver Key Location #26: On the way to Bargate Prison, you will enter an area called the Cliffside Path (not on the maps in the menu screen). In the north part of the map, there is a chest with a circle of mushrooms near it. Dig in this mushroom patch for your key.
#Pointless side not: This area, if you come back to it later in the game, is perfect for farming exp. The enemies keep respawning. As a good character, the physical shield is cheap to maintain. Using this and potions to keep mana up as needed, you can get ridiculously high multipliers. I did this in the original version of the game. Just confirmed it still works. I got a 100x multiplier for the hell of it while writing this.
• Silver Key Location #27: In Hook Coast there is a lighthouse. You will have to fight a boss here. When you get inside of this lighthouse, examine the cabinet for this key.#Note: EpiccRoeley mentioned in the comments that he broke the door to the lighthouse down when he first got to Hook Coast and the key did not spawn. This may be a glitch, so I don't advise trying it. If anyone feels like creating an alternate save and testing this to confirm, I'd appreciate it.
#Note: A few TA'ers have tested this and breaking the door and still found the key (a special thanks to TheOtherBarber and Warboy925 for testing). Regardless, EpiccRoeley may have stumbled on a rare glitch, so break the door at your own risk. If you break it and they key's not there you could load a previous save, but you have to ascend the tower later in the main story anyways, so I'd recommend patience if this is your first play-through.
• Silver Key Location #28: (New Silver Key introduced in The Lost Chapters) When you first arrive in the Lost Bay and get off of the Ship of the Drowned, dig into the grave that is beside the house to your right.
• Silver Key Location #29: (New Silver Key introduced in The Lost Chapters) In Necropolis, fish by the broken bridge near the Demon Door.
• Silver Key Location #30: (New Silver Key introduced in The Lost Chapters) Give the Bowerstone teacher 25 different books to obtain this key.
This is not my original creation and I do not claim credit for it. This info was originally posted on videogamesblogger.com by Ferry Groenendijk. All I did was add a little more detail where needed and remove some spoilers.