While Sela Dillard Green appears in the 1860 Mississippi with her husband William, she does not appear with him in the 1850 South Carolina Census, unless she is entered out of sequence and her is the illegible name second from the last of the list of people in the household.
There are other Dillards who married Greens in Spartanburg, South Carolina: Unknown Dillard m. Adaline Green, dtr. of James Green, probate in 1889; J. A. Dillard m. Eliza Ferguson, probate in 1855.
In addition, there severa Dillards bureid in Spartanburg, South Carolina but all appear to have been born in 1850 or later and would, therefore, not be ancestors of Sela Dillard.