There are two Mordecai students named Garnier in the appendix of my dissertation. Clara and Rosa Garnier may have been from Wilmington, North Carolina; they both seem to have attended from early 1811 to late 1813, and John Garnier is the adult name attached to their account.
Well here's a first: I think Clara Garnier might be the first Mordecai student (that I know of) who was born outside of the United States. Clara Louise Garnier (c1800-1867) was born in Bordeaux, France (according to her tombstone), and emigrated with her father John Garnier and mother Ann Rosalia Boutet to the United States, settling in Wilmington by 1805. Her mother died in 1810 (which might explain why both girls arrived at the Mordecai school in the beginning of 1811). She married in 1822, to businessman George W. Barkley. They lived in Pensacola, Florida, and had nine children born between 1823 and 1838. Here's a photo of her daughter and namesake, Clara Garnier Barkley Dorr (1825-1899). Clara's granddaughter, Martha Sawyer Gielow, was a writer and public speaker, founder and director of the Southern Industrial Association.
Rosa B. Garnier (c1804-1842) was Clara's younger sister. She married Dr. John O. Smith, and died in 1842, at age 38.
The Barkley House, where Clara Garnier Barkley lived, still stands in Pensacola.