Yep, I would and have used it for batting. Some of the very old mattress pads are quite thick and make great potholder filling.

My husbands' grandmother use to use them for making pot holders/ hot pads.

Thanks everyone for your replies. I have a couple of old cotton ones that I have been saving-Anything I buy at thrift stores or garage sale I wash with hot water and some kind of bleach.

a mattress pad made the bestest batting for my friend. She found it still in the package and we decided to try it on a baby quilt. It came out so puffy and looked great

what a great way to re-use! Thanks for the idea!

I've used them (it) for smaller wall hangings that I'm keeping. They work just fine.

Those mattress pads also make great padding for your lovely varnished table top. Make it the size of your table, cover with a nice table cloth and if someone sets a hot dish anywhere on your table it will be protected from the damage! They also make great padding for potholders, hot mitts, or grab mats for your counter tops to protect them.

Sounds like a good idea. But my question is does the cross grid stitching texture on the mattress pad show thru on the top or backing of the quilt where it hasn't been quilted? I'm not talking about being able to actually see the stitching thru the fabric.

The stitching on the mattress pad should not show at all. I've pieced batts many times, and some were layered where they joined, but once the quilt is tied or otherwise quilted, no one was the wiser. (Just don't hang my quilts over the windows at the show. lol) What I'm wondering about is lumping. Some old mattress pads that I've seen were all lumpy. So be careful about the quality. But I have used them and had no problems.

I have used them for doll quilts.