Farmers and ranchers have always been the "greenest" folks around. Having grown up on a ranch/farm, I learned to recycle decades before it became fashionable. Our parents were raised during the Depression and nothing was wasted: it was used up, re-purposed, redesigned, or simply saved for a future use.
Anytime I need to practice a pattern or design, I throw a piece of muslin (or an old sheet) on the quilting frame. Along with my leftover bobbin colors, I top it with some pesky maroon thread that I accidentally ordered 2 of a couple of years ago. It is a good way to use up all my batting scraps also.
After all the doodling is done, I cut up the practice piece, serge the edges and wash them. I save these up until I get a nice bunch and then I drop them off at the Humane Society.
Some lonely doggie or kitty will have a nice soft pad to sleep on.