I do that sometimes too! Instead of trying to store away scraps, I'll tie with whatever is on the table. I hate throwing anything away! (No, I'm not cheap, I'm thrifty!)
Here's one such fly. Approximately 4" long. Barbell eyes, 1/0 hook, a bit of cross cut rabbit, Hackle Flash, the chamois type tail & some chartreuse & gold Polar Flash. All left over from tying other flies. I fished this fly the other day & really liked the action it had. Didn't catch anything on it, but I'm sure it will do well.