Green Apples are a food item rarely dropped when mining a leaf block. They are different than regular apples in which are red. Sometimes Yellow Apples may also fall along with them.
Green Apples heal 2 <3 when eaten and can be given to any green mob except bosses. When eaten in any other dimension, it only heals 1 <3 when eaten and do not make a very reliable source of food when traveling. It is also used for Taming/Breeding Elephants.