Author's Riddles

Riddle (medium)

By Crow

Question: Oh how you love me: to some I'm a must. But to get what you need, you grind me to dust. I am dark and bitter, and when I'm white I lack meat. In winter you drink me, and in spring I'm used in a feast. I am a tree of summer and in autumn I'm a gift on an eve, while all year round I'm quite the reprieve. What am I?