My stash is mostly fabric that "was just too pretty" to leave in the store. I usually buy a yard, figuring that will be enough to be the focus or interesting accent print in most quilts that I make. Some is color that I was sure would match and didn't and others are quilts that just didn't get made. I do impulse buy when I see beautiful colors or print combinations. Much of it is there because when I get a light-bulb-idea, I charge off to the LQS and don't always "shop my stash" first. There is also a lot of leftover fabric.