There's a student named Elvira W. Dupuy in the list of Mordecai school students, compiled by me in about twenty years ago. I'm seeing her listed as a resident of Virginia, at the school for its last three sessions (mid-1817 to the end of 1818), and with Captain James Dupuy as the adult on the account, appearing in the school ledger in June 1817, November 1817, January 1818, and June 1818. That seems like a lot to go on! And Elvira is an unusual enough name, there should be more to find.
And there is. Elvira Dupuy was born in Nottoway County, Virginia, in October 1805, the youngest child born to Captain James Dupuy (1753-1828) and Mary Purnell Dupuy (1758-1828). Her father's military rank came from his service during the American Revolution. Her mother was 47 when Elvira was born, and Elvira's only sister Elizabeth (b. 1803) died young--so a girls' school might have seemed like a good idea for a lot of reasons when Elvira was twelve years old. At age 22, Elvira married fellow Virginian Richard Beverly Eggleston (1797-1853) as his second wife, and the following year both her parents died. The Egglestons had six children. Her last child was born in 1839, when Elvira was 34; and all of them were born in Virginia. She was widowed in 1853, age 48; she lived through the Civil War and died in 1878, a few weeks before her 73rd birthday.
Her grandson Joseph Dupuy Eggleston (1867-1953) was a noted educator, president of Virginia Tech and Hampden-Sydney College, as well as Virginia's state superintendent of public schools (1906-1912).
The Eggleston papers at the Virginia Historical Society Library may have more about Elvira and her family.