Patti, looks like this is my line as well. REALLY confusing how they named everyone after everyone else. I'll try and keep this post simple.
My guy is John Martin Adams, he's living next door to your James Marion/Martin Adams in the 1880 Census in Fannin Co.Texas.
As best as I've been able to figure out, I think they are either brothers or more likely James Marion/Martin is the uncle to my John Martin Adams. I've found James Frank as well in the 1900 census, just trying to figure out who everybody is.
I can't find my John Martin Adams in the 1850 (he'd be about 3 years old and is said to be born in Desoto Co. MS)but I can find James M in Desoto, as you've probably found as well. My guess as of this moment (I just started researching this line again after leaving it alone for a good while) is that my John Martin Adams may have been the son of a JG Adams who is in the 1860 census/Marion County Arkansas. If not, he'd be a son to your James M Adams.
I've also found two 'older' ladies linked to this family, as they seemed to move together as a clan, from Tennessee to Arkansas to Missouri to Texas to Oklahoma. Their names are Luticia and Elisabeth and they are both born circa 1805. Obviously, married into the Adams clan, I have no idea what their maiden names are yet, yet.
My John Martin Adams is in Christian County, MO in 1870 next door to James Adams, who very well might be James Frank. He's married to a Sarah and is 20 years old.