I always have mixed emotions when I finish a spool of thread. Bummer it's gone and Wow! I've done a lot of sewing. I know it's silly but I take the spool and toot a little song of celebrations through it before I toss it in the garbage. I have similar feeling when I finish a cut of fabric. Though this is harder to tell. Since I don't throw away any piece of fabric unless it is less than an 1" big.
Gray is my favorite background.
Sometimes I use them for a whole quilt.