A cracker is not a slave owner or overseer cracking a whip. "Cracker" predates the plantation era; and it refers to someone who would have been too poor to own slaves. It is a farmers who raised only cracked products, such as wheat and corn. "Cracker" was a derogatory term applied to these poor farmers from before the American Revolution.
Sometimes the owners of the general stores wouldn't accept anything but cotton, which forced a lot of crackers to change their crops.