All of these are in the greenhouse scene. You'll also need them all for the Botanist achievement.
The first is a Boar Skull found in the greenhouse courtyard before you go inside.
The second is a mushroom in the first room of the greenhouse. (Eat a second one for the Edible achievement.)
The third is a Venus Flytrap in the second room of the greenhouse.
When you get back to your room with AJ, place them all for the Personal Touch achievement.