Welcome to St Louis!
Unfortunately the May 24-26 weekend is a holiday weekend (Memorial Day) so a lot of people are gone and many of the primary folk locales here in St Louis are not doing their normal thing. That being said there is a big festival being put on in Cuivre River State Park (near Troy MIssouri) about an hour north of ST Louis by Childgrove(our traditional dance group) which will involve 3 days of traditional dance (mainly square and contra dance) to live traditional music with some side jamming and workshops - but mostly instrumental dance/string band style. If you are interested check the website at Childgrove.org and hit the button for "kimmswick". A lot of the areas best traditional musicians will be up there for at least part of it. Unfortunately I am going to be pretty much out of pocket all weekend so I am not available.
If you are in the area during the following week and weekend there are other options I can fill you in on.
Some decent though not exhaustive places to look for music are:
The Down Yonder Calendar on the KDHX radio station web (88.1 fm)site
The Riverfront Times Music Calendar www.riverfronttimes.com
The Folkfire calendar on WWW.folkfire.org
And Dancing Donna's calendar - http://www.dancindonna.com/calendar.html
McGurks is always fun for Irish music but I can't tell what they have planned for that weekend.
Have Fun! Memphis is a healthy 4.5 hour drive and Mountain View Arkansas is well over that. Cahokia Mounds is interesting and close by, Chuck Berry is usually sold out, the Arch is cool, the Budweiser tour has free beer at the end, (if you prefer microbrews try Schlafly.com), There are a couple of good museums and a decent zoo and a good formal garden. Hannibal is 90 minutes north
Bring your rain coat - we have been having unusually wet and cool weather