That's my take as well, but that's how the story goes. I've seen the grave and people leave money around it (what's that about???). I wish I knew more about the person but couldn't find much other than the legend on the internet. I couldn't find the 1860 Slave Census and didn't find a likely white person in the 1860 US Census. Oddly, there's only a handful of folk in the cemetery and that name is glaringly absent from the published list. I may have to head out to the library this afternoon to check out the county history book.
Sounds like Voodoo to me. I wouldn’t be surprised if you found evidence of whiskey or wine being poured on the greave as well. They are offerings to the sprit of the dead.