There was a William Yearwood in Jefferson County, IL in 1850.He was born in 1800 in NC, and is perhaps a son to Frederick Yearwood, married 1795 to Jenny Haskins in Lincoln County, NC.This William (b. 1800) had a son William, (b. 1831) and another son Samuel (b. 1827).Perhaps William (b. 1831) is your William R. Yearwood, father to Samuel Barton Yearwood (b. 1854)?
Frederick's father is the William (Y)Earwood in the Lincoln County, NC 1790 Census.There was also Aaron Yearwood (b. 1797) and Robert Yearwood (b. 1804) in Jefferson County, IL in 1850.I presume they were brothers to William (b. 1800).Hope this hunch helps you find a connection.