Starting with a photograph and some writings left by her grandmother, Thulani Davis goes looking for the "white folk" in her family-a Scots-Irish family of cotton planters unknown to her-and uncovers a history far richer and stranger than she had ever imagined. When Davis's grandmother died in 1971, she was writing a novel about her parents, Mississippi cotton farmers who met after the Civil War: Chloe Curry, a former slave from Alabama, married with...