What Am I Riddles

Question: I run over fields and woods all day. Under the bed at night I sit not alone. My tongue hangs out, up and to the rear, awaiting to be filled in the morning.

What am I?

Question: You find me behind the stars; or in a sixth, seventh, or third.
It takes something round, a computer, and me to make pie.
I am bigger than anything you can think of.

What am I?

Question: I'm the part of a bird that's not in the sky,
I can swim in the ocean and remain dry?

What am I?

Question: You wear me every day but you never put me on.
I will change colors if you leave me out too long.

What am I?

Question: It turns into a different story.

What is it?