Answer:
My tongue hangs out as I run over fields and streets all day. I get tied up every morning and untied at night.
Used left or right, I get to travel over cobblestone or gravel. Used up, I vie for sweet success, used down, I cause men great duress.
As round as an apple. As deep as a cup. All the king's horses can't pull it up.
What is that which, though black itself, enlightens the world without burning?
You eat something you neither plant nor plow. It is the son of water, but if water touches it, it dies.
You use it between your head and your toes, the more it works the thinner it grows.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?