The Steamboat Arabia Museum is in the AAA guide.  It isn't the easiest place to find, but do persevere, it's worth seeing.  The admission price may seem a bit steep, but after you see all the artifacts, you'll feel it's worth every penny.  It's a slice of life from the 1850s, a display of much of the cargo of a sunken steamship that had lain hidden under mud when the river changed course.  How the family found, excavated, and preserved the vessel was quite a story, and they haven't looked through all the boat's cargo yet.  It's a great way to learn what life was like to pioneer in the west -- the boat carried the stuff that everyone needed, hats, shoes, fabric, buttons, tools, hardware; no list could  possibly do it justice.  Plan to spend 2-3 hours in the museum. 

Visitors can watch a conservator working on some of the salvage from the boat, preparing it for display.  Very interesting and educational, too.