Check out local harvest.org to find all available csas in the area first as st Louis has several to offer. Our family is on our third season with three rivers community farm and we really enjoy the variety and quality of our produce.
Another one we have used in the past is la Vista CSS in Godfrey, il. They request that you volunteer at the farm monthy, which proved difficult for us as we live in st Louis city.
If I can answer any more questions regarding csas in stl, let me know. I'm not on mothering often as I am chasing my toddler around most days.