Answer:
I am needed for most animals and hardcover books. What am I?
You throw me away, I find my way back. Traditionally, I'm wooden with an arch in my back. What am I?
When young I am sweet in the sun. When middle-aged I make you gay. When old I am valued more than ever.
As a state in the USA, I am round on both sides and high in the middle. What am I?
I am a fruit with seed on the outside. What am I?
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.