Fiberfill?

Does anyone have any strong opinions on fiberfill? I need to re-stuff Shep, the doggy I got from my Grandma, whom Patches is somewhat modeled after.

I'm not wanting to use the cheapo poly-fill stuff you buy @ Joanns - I was going to try to buy something from a natural fiber... But I'm not sure of a great source to find cotton/wool fiberfill...