In researching the children of Presley Sylvester MARTIN b. January 8, 1822 in VA d.November 25, 1895 in MO and married December 10, 1845 to Lucinda HALLEY, b. abt 1824 in Gallia, OH, d. April 23, 1886(dau of Samuel HALLEY and Letty THOMAS), I came a cross a very helpful reference titled, "History Of Hickory, Polk, Cedar, Dade And Barton Counties, Missouri, 1889." Published by Goodspeed. Pages 926, 927.
The biography references Samuel HALLEY and Letty THOMAS HALLEY as the grandparents of Samuel N MARTIN, b.abt 1845 in OH (son of Presley Sylvester MARTIN and Lucinda HALLEY.)
Furthermore, the biography makes a direct reference to the Lucinda HALLEY MARTIN heritage in the following passage; "The maiden name of the Doctor's [Samuel N Martin]mother was Halley, and she was a great-neice of Gen. George Washington. She is a descendant of Col. Fielding Lewis, who married Elizabeth Washington, only sister of Gen. Washington."
You can find the complete article at: http://files.usgwarchives.net/mo/barton/bios/m6350009.txt
I should add in the 1880 Census for Cedar, Dade CO., MO it lists the following individuals: Presley Martin 57y, Lucinda Martin 55y, Maud Morgan 7, Herbert L Gaty 1. For Lucinda it lists both her mother and father as being born in VA.