I would take a look at Cassuners Patrick U. S. Census 1820 Charleston Neck, Charleston, South Carolina. Also William F Shackelford in close proximity, on the same Census, Same Location. Since Elizabeth Shackelford 1814 indicates born in South Carolina. I would also investigate Robert A. Patrick U. S. Census 1830 Talbot, Georgia. He appears to be the correct age based on the 1840 Census information and appears to be someone of status for his age. He also appears to be similar in status as the 1840 Hinds County Census. Additionally there were also established travel routes during that timeframe from that area of Georgia across Alabama to Mississippi. Other families are established and documented as taking the same or very similar route.