My mom gave up crocheting a few years ago and let me have a biiiiiggg box of yarn, including several granny squares. I put some of those together into a baby afghan for a friend http://morning-glory-garden.blogspot.com/search/label/afghan, and then forgot about the others, while chipping away at the rest of the yarn for various projects. Then one day I laid out 9 of them on top of a pretty disreputable-looking corduroy-covered ottoman, and it was nearly a perfect fit.
I joined them with green and gold yarns left over from something else and then crocheted round and round, in various shells and double and treble crochets, till the sides were long enough to reach the floor. That was a little tricky as I had to keep checking and often decreasing in subsequent rounds to make sure the sides fit snugly enough.
Apparently Cosmo thinks it was made for him. He didn't care much for the faded rust-colored corduroy but he obviously recognizes how well the new cover goes with his coat!