Theodore Gourdin (1764-1826)  married Elizabeth Gaillard (1766-1835) . Their children were Robert M. Gourdin, Theodore Louis Gourdin, Esther Gourdin (who married Silas P. Holbrook), and Elizabeth Gourdin (who married Peter Gaillard, Jr.) Elizabeth and Peter Gaillard's daughter Harriet married Samuel David Stoney, and their son was Samuel Gaillard Stoney (1853-1926).
Theodore Gourdin's Papers are included among the collection Gourdin Family Papers, 1707-1903, Call Number 1038.00, and include records for Murray's Ferry and Linud's Ferry plantations.
Records for Red Clay Plantation are included in the collection Gourdin Allied Family Papers, 1707-1903, Call Number 1038.03.
The will of Theodore Gourdin is among holdings at the Charleston County Public Library's South Carolina Room.
The Gourdin-Gourdine Family Association website contains much information on French-African Americans in SC. They publish a newsletter called the Gourdin-Gourdine Family Quarterly, which you can subscribe to.
The book The Gourdin Family by Peter Gaillard Gourdin contains references to many historical documents for the Gourdin family.
There you can purchase the book Family History Book Gourdin[e]: A French-African American Family from South Carolina, (1830-1994), written by John Raymond Gourdin.
References Cited Above:
 Collection description, Gourdin Family Papers, 1707-1903, South Carolina Historical Society. Call Number 1038.00.
 Collection Description, Elizabeth Gaillard Gourdin Estate Record, 1837, South Carolina Historical Society. Call Number 43/0846.