I pick up the bags of leaves/grass/etc. that my neighbors put out for pick up and spread them around my (heavily treed) yard for ground cover. Results are mixed -- my favorite is pine needles, leaves are OK, grass clippings aren't ideal for my purposes, and it's not always obvious what I'm getting (plus I end up with pine cones and gum balls, neither of which I really want) -- but certainly functional, and free. Plus better for the environment and my tax rate, as if I didn't pick them up the town would, in big trucks.