Answer:
Flat as a leaf, round as a ring. Has two eyes, can't see a thing.
A hill full, a hole full; yet you cannot catch a bowl full. What is it?
At the sound of me, one may dream or stamp their feet, At the sound of me, one may laugh or sometimes weep.
My life is often a volume of grief, your help is needed to turn a new leaf. Stiff is my spine and my body is pale. But I'm always ready to tell a tale.
Upon me you can tread, though softly under cover. And I will take you places, that you have yet to discover. I'm high, and I'm low, though flat in the middle. And though a joy to the children, adults think of me little.
You use it between your head and your toes, the more it works the thinner it grows.