There's a student named Lucy Edmonds in the rolls of the Mordecai school, attending from mid-1814 to the end of 1816--five sessions, a relatively long stay. She seems to be from Northampton County, NC, and the adult attached to her tuition payments in the ledger (1814 was named Howel Edmonds. She must have been ill during her stay; a letter from Rachel to Samuel Mordecai dated 23 January 1816 notes "Miss Edmunds dangerously ill upstairs (she is now convalescing)" among the many "glooms" of the school that winter (letter in the Mordecai Family Papers, Southern Historical Collection, Chapel Hill).
In the later Mordecai correspondence, she turns up in a letter from Caroline to Ellen, April 1822, because some of her younger cousins (Mary and Lucy) are attending Caroline's school in Warrenton that season. (Caroline Plunkett to Ellen Mordecai, 22 April 1822, Jacob Mordecai Papers at Duke; "little Mary Edmonds" mentioned again in a letter dated 18 January 1823, still a student.)
One man named Howell Edmunds (with this spelling) is relatively easy to identify: he was a colonel during the War for Independence, served in the Colonial Assembly, and in the Provincial Congress, and in the North Carolina House of Commons after statehood. He was also sheriff of Northampton County, North Carolina. He was born about 1730, married his cousin Lucy Nicholson (1737-1811) in 1757, and died.... in May 1814, just before the student Lucy appeared at the Mordecai school. (It seems Col. Edmunds had a sister, wife, daughter, a daughter-in-law, and at least one granddaughter all called "Lucy Edmunds," and probably some nieces too.)
The Col. Howell Edmunds seems to be the student Lucy Edmunds' grandfather. Her father was the Colonel's son, also named Howell Edmunds; her mother was Elizabeth. She was one of eight children.
And that's where the trail ends--I can't find a mention of this Lucy Edmunds (or Lucy Edmonds) beyond the 1810s, except the mention in Caroline's 1822 letter. Anyone know her fate?