I'm sorry to hear about your mom. I like everyone's ideas about making a quilt out of them. If you have some left over or some with some stains which won't come out you could make really cute house slippers and guest slippers out of them. there was a great flickr post I found the other day on the topic. *searching*
here's the flickr pic with link to her blog and instructions on how to make them.
It's off topic, but if your mother was an avid baker or loved to cook I saw a great idea for transforming handwritten recipe cards into tea towels. It's also a nice way of remembering someone and very useful as well. Here's the link if you're interested:
http://blog.spoonflower.com/2012/07/...ea-towels.html