L.D.
I highly recommend MOMS Club - http://swstlcountymomsclub.webs.com
We have about a dozen events every month, and our chapter is right in your area! Sometimes we go to places like the zoo, science center, Grant's Farm, Magic House, etc. or other times we just go to a nearby playground or somebody's house. Once a month we have a social where there is plenty of room for everyone, so the moms can talk and the kids can play. We also do Moms Night Out!! I have made some great friends, had lots of fun, and learned a lot too. I hope you will check it out!
Here's another group - http://groups.yahoo.com/group/sahmsclubstlouis
It tends to be more e-mail and less in-person meetups, but they do have events from time to time.
In both groups, the moms are wonderful people. If you join either of them, please let me know. I would love to be able to personally welcome you.