For the old-time Tune of the Week, 2/20/16, this comes from the fiddling of Emmett Lundy, whose mentor, Greenberry Leonard, was born in the early 1800's and died in 1892. Thus it probably harkens back to before the Civil War. Sheep Shell Corn is recorded as a poem in a 1920's publication called Negro Folk Rhymes, so I can imagine perhaps slaves sang this song as they shelled corn (a tedious job) or as they danced to their own music. I used some of the verses from the TOTW discussion: http://www.banjohangout.org/topic/315336.