Answer:
I am not a toy though many use me for pleasure. I have a butt but I cannot poo.
Flat as a leaf round as a ring. I have two eyes but can't see a thing.
I am rarely touched but often held and if you are smart you'll use me well.
What can you hold in your right hand but not in your left hand?
What do you call a bear in the rain?
Black we are and much admired. Many seek us if they are tired. We tire the horse, and comfort man, and turn White when we've fulfilled your plan.