MoyshaKing

so can anyone explain how to add custom features to biomes, i've been trying to make my a custom mushroom that spawns in the forest but nothing works. I've seen so many different ways on how people do that and I am completely lost now.

So I am currently making a custom crop for my mod, and when when i plant it looks like wheat type of crop ,so like there is 4 textures of the crop in a square, but if you plant pumpkin there is just one sprout coming from the middle, so how do you do that?