I would use Warm and Natural (or White and Natural). Joann's sells it by the yard and if it's not categorized as a batting, you can always use your 40% off coupon.

What is a Quillow????
TIA for the info!

It's a quilt that has an attached pouch, so you can fold it up, into the pouch and then it looks like a pillow (or is a pillow).

Oh and Jen, another thing just came to mind - you could also use fleece. Nice and cozy.

I've seen quillows made with fleece. They are very warm and cozy. The kids love them.

I have used lots of things as fillers. This is a good place to recycle & use things on hand or to purchase things from thrift stores such as blankets or comforter type bedspreads.

About 10 years ago, I bought 300 lbs (min purchase wholesale) @ $1 a lb of seconds in comforter fabric, rejects of some constructed & some just the fabric. It was sight unseen at that price. I had many orders to make fabric bags for people that sold Home Interior to use to take their items to homes for the parties. I had a friend who was a dealer & she got me to contract through her. To my dismay, I had tons of solid light pink when I got home...not a good color to hold up well for them to pack their items to take to parties. I had to think of something to dispose of that & replinish my wallet for my expense. I made quillows & used that instead of polyfil. It was actually easier to use & I had less trouble encasing it without the foot of my machine catching in loose polyfil. For colder weather & outside sports events, the fabric & nylon mesh that was on either side provided a layered effect for holding in body heat.