In the crafting world, these are called orts. And some people get super creative with them! I’ve seen them user to decorate cards, to make collage art, to fill little clear Christmas ornaments or felt animals, etc. I’ve been saving the ones from my current project because I want to take a picture of the finished cross stitch next to all its orts. It feels like a visual representation of “you can’t make omelet without breaking a few eggs”, you know?