If you mean the Martha Kent version from the Superman Movie (Chris Reeves version), you could have the Smallville Quilting Club going to Wichita to go to a quilting exhibition. (Quilting is still very big in my small town. Actually ALL crafts are big in this small town, which is bigger town than the Superman Movie's Smallville, but still has more beauty salons, craft stores, and auto parts stores than a town this size should be able to support.)
If you mean Diane Lane (from MoS), I'd probably have her be a stronger woman (running her own farm as a business), much like our LnC Martha Kent would be, only without the interest in art. You could always have it be a group from the Smallville Historical Society going to Wichita to see some historical exhibition.
THE Little House of the Prairie (of Laura Ingalls Wilder fame) is in Kansas. So, you could have Martha taking a group of school girls, from a book club that she runs through the Smallville Library, to Independence, KS to the Laura Ingalls museum, there. Although, it would be a great disappointment for all if the driver got sick.
I guess the trip could always just be postponed to a later date.