Scrap quilts are the best! Most of mine are sorted by color, but they still end up randomly in tubs and boxes.
The guild does a lot of square exchanges. Many times we make the same square each month, but in different colors. I always have plenty to pick from.
I even make the backgrounds scrappy in my quilts.
I used to save all the smallest crumbs that were really too small to sew, but now they all go into muslin "sacks" I make. I also add in my batting scraps. When they get full, I stitch them closed, make a removable (so it's washable) fleece cover and they go to the kids' dogs for a new bed pillow.
Sometimes, after a top is finished, I make an extra block to match the front for a label. Lately, I piece together the rest of the scraps, whatever size they are, like a puzzle, and use them for part (or all!) of the backing. Often I can pull other fat quarters or pieces of the right color from my stash to make the backing big enough. Using up the stash (never!) and don't have to buy more fabric for a back.