Longtime field laborers in the Mississippi Delta said in a lawsuit that they were asked to train white guest workers from South Africa before losing their jobs to them. For more than a quarter-century, Richard Strong worked the fertile farmland of the Mississippi Delta, just as his father and his grandfather did, a family lineage of punishing labor and meager earnings that stretched back to his enslaved ancestors brought from Africa. He tilled the soil, fertilized crops and irrigated the fields, nurturing an annual bounty of cotton, soybeans and corn for a prominent farming family. “I’ve been around farming all...