I add alfalfa pellets, ground limestone, peat moss and other limited additives. Most kitchen waste is acidic, as is peat moss. I am not doing it to make a rich soil but to loosen it.
Found a children's therapy place nearby that has several horses. I have no idea if they use the manure or have a contract to dispose of it, but am checking. Thanks for ideas.
In my old neighborhood several bagged their lawn clippings. I usually took a bag or two on trash night every week or so [if it had not been sitting in the sun for a week to mold]; contents were then used as mulch and also worked into the soil. This new neighborhood has mostly non-baggers but lots of weed seeds in the bags when they are used, so I avoid them here.