There's a Nancy Snead shown being married to a Lawrence Horne in the "Early Marriage Bonds, Richmond County" webpage: Horne Laurence Snead Nancy 22 Mar 1803 Jesse Cole
It's interesting to note that the JP or Pastor is Jesse Cole, a family name that is prominent in the early Snead history (Snead Notebook).
This would work reasonably well with a birth date of 1771 for your Nancy Snead in the Snead Notebook. However, the Snead Notebook also notes that Henley's daughter married a "Mr. Brown" at some indeterminate date--she's mentioned in Henley's will dated 1815.
My puzzlement has been to figure out whether this is "my" Lawrence (van) Horn who is said in family documentation to have married (late in life) Ann Crosland Snead/Sneed with known offspring including Ann Crosland Horn, Temperance Buford Horn, and Daniel Alexander Horn (my g3grandfather). Ann Crosland Snead is given dates of 11 April 1773 (Sneedsboro, Anson Co., NC) - 1854 (Cheraw, Chesterfield Co., SC) and Lawrence Horn 1756 (at sea, near Philadelphia) - 1830 (Cheraw, Chesterfield Co., SC). The earliest birth date for a child of the marriage is Sarah Horn (7 Feb 1804) and by the date of Henley Snead's will (1815) there were 4 Horn children (Sarah, William Henry/Henry William, Temperance Buford, and Catherine).
There certainly is a lot of name conservation and crossover in the Horn family with the known Sneads, Croslands and Bufords. But the same family lore has Ann Crosland Snead the decendant of Israel Snead andTemperance Buford-Samuel Snead and this has not been documented in any published source, nor have my sporadic postings on the message boards been answered by people who might know. It would work if Henley had mis-remembered the husband of his daughter Nancy in his will -- but the birth date in the Snead Notebook is a fit only to the month with that of Ann Crosland Snead in the family documentation.
The family documentation I refer to is an extensive typed manuscript that was compiled by Nannie/Nancy Horn Ivey daughter of Daniel Alexander Horn. Bits and pieces of it have been published on the web before (it's pretty widespread) but I've never seen any independent links of Horns, Sneads, and Croslands outside of this.