Shadow Kisuragi posted this link to his world which has enough for all the emeralds without having to reload the save over and over. Here it is!OR
If for some reason you have trouble with that world, here is another one posted by II NeoReapeR II
If for some reason you're having an error when trying to load up the maps. Make sure you've updatrd the app. If that sounds already been done, you'll need to reinstall the game. Thanks to several users in the comments :)Original
Here's the link to the dropbox containing the world.
As for the instructions on using the world... Whenever you spawn in, right click the villager directly in front of you, and trade him the 19 wheat in your inventory for one emerald, this will give you 1/30 for the achievement.
With your new emerald, click to the far right tab of his trades, and swap the emerald for 3 bread. This will get you another tick on the achievement counter, bringing you to 2/30. Save & Quit, then re-import the world linked above, rinse and repeat 15 times until you unlock the achievement :)
As for anybody wondering a quick way to replicate this on another device, I used the seed "village pls" it spawns you in the middle of a double village. I farmed some of the wheat and found a villager willing to trade for it. From there the rest is history. Good luck!