The Berry grows on Berry Bushes, and restores 1/2 of a hunger shank.
The Berry takes 1/3 of the regular time to eat, and is picked with a right-click. The berry bush will regrow, and can be farmed. You can pick up the Bushes with a pair of Shears.
be sure to eat that fruit salad!
Berries are also part of the Village and Pillage update, Named Sweet Berries.