I have quite a bit of info on the Munns of the Laneburg - Mt. Moriah area, but don't see specifically a J. B. Munn. Could he be James Munn, born about 1805, died 1877 at Mt. Moriah (Nevada County AR) and was the son of Duncan Munn and Catherine Smith Munn? If so, I have more on this family.

I also have photos of Thomas Munn, as well as the family consisting of Eunice Munn Cummings, Melvin Munn, Owen Munn and George Munn.