Create a nutrient-rich base layer by collecting grass clippings and raked leaves to spread over the bed, as long as you didn’t use “weed and feed’ or other broad-leaf weed killers (flowers and vegetables are broad leafed). With vegetable gardens, usually we take away the plants that were growing there this year to reduce the possibility of diseases or insects from wintering over. But any vegetable plant not affected by disease or insects can be chopped, and left behind. The leaves from corn plants, the overgrown lettuce heads, the tops of carrots and so forth are a starting point. But don’t forget all those leaves that fell on yours or your neighbors’ lawns. Pick them up with your mower bag and they’ll be shredded and ready to improve your vegetable garden.