States: Florida: Gadsden
You might try looking for Mashburn as the last name instead of Washburn. A lot of the Washburns listed in the 1860 Gadsden County Census should have been Mashburn.
This mixup has caused me lots of confusion in looking for my great-grandmother's family. Her name was Nancy Ann Mashburn who married J. J. E. Slade (Joseph) in 1874 in Gadsden County. Family history and their marriage records clearly say Mashburn.
Joseph Slade's sister, Esther Slade, married Jeptha Marion Whitaker in 1867 in Decatur County, Georgia. Another sister, Margaret C. Slade, married Benjamin Franklin Harrison in 1870.