Answer:
I am tomorrow's yesterday and yesterday's tomorrow. What am I?
I am the key that is the hardest to turn
I ask no questions but receive a lot of answers
I start in little but I end in full you'll find me in half and complete.
I am asleep when you are awake I am awake when you fall asleep. I can fly but no feathers to aid my flight.
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.