He may be a child of William O.and Mary (McCrary) Blanton and brother of Napoleon Blanton. They appear with her in the 1850 Jackson Co., MO census. Their father is missing, but apparently not dead. Benjamin appears in the following censuses:

1860 McGhee Co., KS, Cumberland Presbyterian pastor, wife Lucy C and daughter Augusta, 1 yr.

1870 Carroll Co., MO, physician, wife Ann, 2 children, apparently Ann's, Augusta Ann, 11 yr., and Claiborn F., 9 yr., (probably by Lucy) and Benjamin, 1 yr. The children seem to be grouped by parents, rather than strictly by age. Since Augusta was a rare name among Blantons, it would be highly improbable that this was a different Benjamin.

In this article, he was said to be a Methodist missionary. They may have misidentified the denomination, though:

http://skyways.lib.ks.us/genweb/archives/1912/h/humboldt.htm...

This would explain why he moved around so much and how he could have met Mary Ellen Schwabe. Her father ran a hotel in the town of Columbia in 1880. Benjamin may have been travelling or lived in the hotel for a time while on a mission.

Claiborn and Benjamin apparently did not survive until the 1880 census, preventing us from tying the two families together with the children. The birth places of the parents, although the category is often unreliable, fit William (KY) and Mary (NC or TN).

I found the death certificate of Minnie Augusty Coulter at Family Search. She died in Maricopa Co., AZ in 1934. It lists KS as her birth place and parents as Benjamin Blanton and Lucy Ayl. She apparently married George W. Maddix in 1879 in Coffey Co. , KS (Family Search) and they appear to be in the 1880 Shawnee Co., KS census, even though the parent information is wrong. At some time, she appears to have married John N. Coulter, since he signed her death certificate and remarried shortly afterward (Family Search). However, I cannot find her in any censuses after 1880.