Dave Hillebrand at Prairie Grass Farms raises lamb in New Florence, MO. He sells his meat at the Maplewood and Tower Grove Markets when they occur. I know he also sells his lamb meat to Local Harvest grocery store.
Just a quick note, my Dierberg's has some American Lamb in their meat department now. I can't imagine that we get a lot of call for it in our neck of the woods so it must be a chain wide decision. They had chops and ground lamb, that I noticed.