From the book "Richland Homecoming 1838-1964, page 35+:
"In 1856, three young men came from New Jersey and started an academy in Richland which was in operation four years. The principal, Mr. Naylor was the author of a text-book on arithmetic and geography."
There is a bit more in the book on page 98 which I will scan and send to you if you want. I see no mention of an Underwood.
Richland is in Keokuk County, just north of the Jefferson County line.
Sam Cook, Milan, MO