My mother remembered the line "buzzards [or perhaps crows] and the flies pecking out his [or perhaps her or its] eyes" from a song her mother sang to her in rural Mississippi when she was very young. She'd been struck by the gruesomeness of it. I figured the internet would let me find it pretty fast and sure enough I find it on the first hit. For the record her family were white farmers who'd been in Mississippi at least as far back as 1819. I seriously doubt they considered it social commentary on the plight of slaves.