Jennie,
I searched my cousin Betty Joan's comprehensive Herndon compilation on "Marg," "1859," and "Sloan" with no results. Nevertheless, I would be very surprised if Margarite/Margaret, a Herndon born in Florida, isn't connected to me somehow. No matter how comprehensive a compilation is, it's always incomplete. Do you have a location?
My Herndon relatives of the same vintage are:
Generation 97 • James Perry Herndon (Fla 1839.Sep.01–1892.Apr.26 Fla); born & died (murdered) in Hamilton County. He was the ninth of twelve children born 1820–1849 to (generation 96) Richard and Pinky Padgett Herndon, and was either the first or second born after they moved to Florida. Married Eliza Downing (Fla 1841–1914 Fla; daughter of [gen 96] Renatus & Keziah Hiers Downing) on 1859.Nov.17 in Hamilton County. The Downings and Herndons had neighboring farms about three miles west of Bellville in Hamilton County, and three of the Herndon children (Martha Ann, James Perry, Levi Hancel) married (1850, 1859, 1866) three of the Downing children (William, Eliza, Nancy), producing twenty-four Herndon–Downing double first cousins in generation 98. James Perry and Eliza had nine children born 1860–1884. James Perry enlisted 1862.May.10 as a private in Captain Frinks’s Company F, 5th Florida Infantry, CSA, at Jasper, Florida. His enlistment papers describe him as five‑ten, with a dark complexion, blue eyes, and dark hair. He was wounded — he lost one or more fingers — at Chancellorsville on 1863.May.03, and on 1863.Jul.02 he was captured at Gettysburg. Two or three days later he was confined at Fort Delaware for the duration of the War; he was released at Fort Delaware after swearing his oath of allegiance on 1865.Jun.10. He apparently made his way home to Florida by September because my great-grandmother (generation 98) Manerva Ann "Nervie" Herndon, his second child and daughter, was born 1866.Jun.18. At 15, Nervie married John C. Cannon, a widower with two children (Kate 12 & John 10), and had thirteen children with him 1882–1908. My grandmother (generation 99) was her second child and oldest daughter.
My approach in recording genealogy is to disclose genealogical data in the form of the ancestor's story, which I believe casts ancestors as the real people they were instead of just names and dates on a list. I'm entering my data slowly and manually, and I'm being careful to look for existing profiles before creating a new one. However, my worksheet for Nervie's ancestors is on her father JP's (Herndon-562) profile. Much of the information there will eventually get moved elsewhere. Meanwhile, you may find something useful.
By the way, it took me ages to find Nervie's gravestone (because it read "Nervie Cannon" and all I knew was Manerva) and death certificate (because it had her name as Mrs John Cannon [sic Jack]* and her parents as Mr & Mrs Herndon). JP's body was thrown down a sinkhole by his murderers and was never found, so I didn't think to look for her by looking for him, but it turns out he has a centograph next to her.
If you know the names of Margaret's siblings, try their death certificates, and also her children's. For example, on my grandmother's older half brother John's death certificate, I discovered that Nervie & Jackson may have partly named my grandmother, Frances Elizabeth Cannon, her first daughter, for Jackson's first wife, Sarah Frances Moore. Or not, if the provided info was wrong — John's birth date was off by a year on the same death certificate. Or that could have been a math problem since his birthday was calculated from his age at death.
Other avenues to explore. Look hard at neighbors on the 1870 U.S., 1875 Fla, 1880 U.S., 1885 Fla, and 1900 U.S. censuses. (The 1890 census is missing; not sure about the 1895 Fla census.) If you are African-American, compare the 1870 census household by household with the 1860 census, paying particular attention to slave schedules. Remember that many — perhaps the majority — of country people were illiterate then. Census takers took shortcuts, and there's no telling what rooster provided the information.** Many names are misspelled in the records; Herndon is often misspelled Hendon and Cannon as Canon. People used their initials on official records or were called by their middle names, which would be an initial in the records. Another source to check is the local news (i.e., gossip) columns of small-town weekly newspapers,*** which you can search through the online Florida state archives.
Good luck,
Deborah
* His full name was Andrew Jackson Cannon, and he was called Jackson or Jack. His father's name was John, and he named his oldest son John (the subject of death certificate discussed).
** My mother's other grandmother has a birth place of Georgia in every census for which she is head of household, but when her son, my grandfather, is listed as head of household in the 1910 census, it says she's born in Florida. But I know he wasn't in White Springs in 1910; he was about seven miles northeast of the town, on the family farm, with my grandmother, who I can't find anywhere in the 1910 census.
*** I identified a great-uncle's widow's family that way, by finding a note in Lake City's "News about Town" that her brother was visiting her.