Recycling clothes that were too worn for Goodwill, leftovers from things I'd bought for other projects, super duper clearance sales, projects that were PIGS and I'd forgotten why I bought the material...
My favorite pieces are gifts from my grandma. This year, she asked what I wanted, and I told her "fabric"...and she pulled from her own stash since she doesn't quilt anymore. :) I'll admit that the patterns are interesting, but I'll find something scrappy to do with them.