You may need to give some hint of the general area where you live. Kind of hard to answer your question without knowing where you are and how far you are willing to go. Some towns make compost out of organic trimmings. I know that Springfield, Mo does. Some give it away free to residents, but charge outsiders.

I would say your best bet is to build on what you have. Clay can be turned into very good soil with the addition of lots of organic matter, manure, shredded paper, etc. Check out the soils forum for ideas. Try digging a hole, filling with water and time how long it takes to drain, then talk to the folks on the Soils forum. When building beds, I have been known to dig the soil out and sift the rocks out if it is too bad. Takes time, but you can really see results when finished. If you can use at least 50% native soil it will save lots of money. Sometimes the soil you order in is no better than what you already have.

Call (or go by) Horse Boarding stables. Most of them will let you have manure from the barns for free....sometimes, its even aged.

Oops! Forgot to mention that I am in the Little Rock area!

Large enough city...maybe they are composting tree trimmings, grass, etc. Personally, I would not use the stuff from the sewer plant on any food plant. Using it on ornamentals would not bother me. We used to get it and spread it on the lawn and around shrubs and trees, but that was 30 years ago.

Stables, dairy barns, and commercial rabbitry operations...all are potential sources of manure. Saw mills for sawdust...don't worry about nitrogen..just add enough to help break it down into good organic material. If you can't find the finished stuff..make your own. It really is not as hard as some folks make it sound. It can be as easy as tilling it into the soil to start a soil improvement program and then build the piles to topdress with to keep it in good shape.

Take a soil sample to the local University of Arkansas Extension Agent, usually located in County seat. You can do that after all the organics are decomposed..then you will know what else it needs.

Along with the horse boarding and stables, try a local therapy riding school. We have one around Diamond Mo. that has fresh and aged manure, they are always wanting to give it away. When I get my raised beds put in, that's where I'll get some of mine.
TJ

oh, i want one of those power lawn vaccumm that go behind my riding mower !!!we have horses on 40 acres, and oak leaves, lawn clippings--all that "gold" i'm getting too old to rake up--but can you imagine if i could get it on my no-till mulched garden? but--unless i win the lottery------

Wishful thinking, I live in Searcy. They have a mulch yard and the good old boys that work there will let you pick whatever pile you want it out of. If you want the old stuff they'll scoop it for you. It'd be best to sift it through a screen. They don't care if you're from the county or not. We put a tarp on our trailer and then cover with another one. The down side is they're not open on the weekend. Take the first Searcy exit and just keep going down main street until you've gone all the way thru town and out the other side 3 or 4 miles.

Wishful, I'm also in Little Rock and I get my compost from American Composters.
It's about $30 for a truck load and they'll load it for you.
Hope this helps.

Thanks everyone!