If you keep a small waste can on the floor next to your sewing area, check it for quilt blocks that fell into it while you were sewing.
I threw the last 6" by 9" FUSSY cut piece of fabric for a quilt away because I did not check the waste can. Just bagged it up and put it in the trash can. Of course, I discovered my loss the day AFTER trash pick up!
I had to make up that piece by more fussy cutting and a once in a life time absolute match of sewing two fussy cut pieces together to make the block. The last block is also different from all the others, but is so well disguised that the eye just wanders past it and assumes it's a match. You can't tell the block is sewn from two scraps unless you look at the back, either.