Answer:
I can be thin but not fat; in your body but never on your placemat. I'm always better when I'm fresh but you'll never see me in the flesh.
I'm the source of all emotion but I'm caged in a white prison.
I can only be played on a windy day
What has roots that nobody sees and is taller than trees. Up up up it goes and yet never grows?
Flat as a leaf round as a ring. I have two eyes but can't see a thing.
The answer I give is yes, but what I mean is no. What was the question?