Answer:
A circle of stones, never in rows. Stacked one on the other, mystery it sows. What is it?
What has three ways out and just one way in?
The man who made it didn't need it. The man who bought it didn't use it. The man who used it didn't want it.
What has roots as nobody sees, is taller than trees. Up, up it goes, and yet never grows?
Round as a button, deep as a well. If you want me to talk, you must first pull my tail.
Strip the skin under my skin, and my flesh you'll reveal. It tastes sweet and tart, now throw out the peel. What is it?