A cheap way to make a back yard a better environment is to reduce the size of the lawn! The health of trees and bushes can be dramatically improved by increasing the circle of mulch underneath them. Trees naturally grow with dead leaves and natural litter around them - try to find a wild tree without natural litter beneath it. Traditionally, we plant grass right up to the trunks and mow it, maintaining a hard surface. Instead, spread mulch from the trunk about 2" thick (do not ever let it actually touch the trunk since this causes the tree to grow unnatural roots near the trunk instead of fanning out its fine feeder rootlets) all the way out to the outermost edges of the branches. In the fall, just leave the fallen leaves there! Less work! You can plant many bulbs in the mulch this fall for a gorgeous spring display next year. In spring, you can plant a groundcover in the mulch, such as Pachysandra which is not native but certainly better for the tree and the environment than an unnatural, hard surfaced lawn. Rainwater runs off a lawn but groundcover absorbs it and helps nourish the tree. Also, less lawn means less mowing, which means less gasoline exhaust, noise and dust!
I reduced the lawn next to our driveway and created an attractive new curved edge to the remaining lawn. This particular lawn was very matted, so I cut out the sod in the shallowest cuts possible so as not to damage the fine feeder roots. I also added a little new soil in areas where the old soil was gravelly or sandy. I used Pachysandra, which is easy to get in flats of 50 little plants. Plant each Pachysandra about 5" apart, then add mulch to keep moist and stop erosion. Keep the Pachysandra moist by sprinkling once a week. I would have preferred a native groundcover but could not find one suitable for the site. Here is a great search engine for native plants you can buy at the Native Plant Trust in Framingham: https://plantfinder.nativeplanttrust.org/Plant-Search