Geri, hopefully you're still tracking this thread. I think your Mary ties into the Thompkins/Tompkins family I've been researching for the last five years.
Two years prior to Mary's wedding, a Rachael Thompkins also married in Hardin Co, KY, and one of her witnesses was Benjamin G. Thompkins. Benjamin G. is one of the individuals I've been tracking for awhile. I just thought to look again at Hardin Co's online records, and discovered Mary & Rachael this week. I'm in the process of researching their lines before I upload an update, but you can see what I have here: http://wc.rootsweb.com/cgi-bin/igm.cgi?db=pgoldenman
. In a nutshell, I think Mary was one of 8 siblings/cousins (3 boys, 5 girls) who moved to Greene & Jersey Co, IL; five of them then crossed the Oregon Trail. My 3ggrandmother is the baby of this group, and stayed behind in IL.