I think I may have information concerning your Banjamin Tatman.The one I have was born in 1795 probably in Maryland.Benjamin's wife was Abigail Harris and they had four children: Malissa b. 1834, Bethina b. 1837, Oliver b. 1839, John b. 1841.
This Tatman family was in S. Bloomfield Twp, Morrow Co (formerly Knox Co), Ohio in the 1850 census.They may have previously lived in Hocking Co, Ohio as a contact gives son, John's birthplace as Hocking Co.
Oliver married a Mary and they had: Charles & Warren.
If this is the family you are interested in I would love to share information.