The flapple is a food item that can be used to cook Flapple Fizz, and Flapple Pie, it can also be eaten on it's own but you will benefit more if you cook them. It is obtained by Chopping Trees (drops, gives assortment of flapples), Acorn Beasts (drops, gives assortment of flapples).
Game Description: "Some kind of alien fruit with wings for some reason."