Mary Martha Simpson was the dau of Albert Lomax Simpson Sr (1833-1923) and Nancy Jane Stogsdill (1837-1900). On 19 Feb 1880 in Pulaski County, KY she married William Mattison Barrett, son of John J Barrett and Mahala Combs. There are several family members; see below:

Albert L Simpson (23 April 1833 - 21 March 1923) was the son of William T Simpson and Temperance Beshers (Brashears) from Rockingham County, NC. Albert was counted on the 1850 Census with his parents and sister Elizabeth living in Hawkins County, TN.
The family moved to Pulaski County, KY around 1852. Albert ran off with Nancy Stogsdill (their first child was born in February 1854). A report in The Interior Journal (Stanford, KY) on 8 June 1886 reported that Albert L Simpson married Nancy Stogsdill 30 years or so after they first began living together and raising a family. Simpson's death record states he was buried in Stogsdill Cemetery.
Sister: Elizabeth Simpson Roberts #23100119
Source:
1) Marriage Record: 3 June 1886 (Albert Lamex Simpson Marriage • Kentucky, County Marriages, 1797-1954 (found at) https://www.familysearch.org/ark:/61903/1:1:QKJ9-6RVD
2) Birth of son George Washington Simpson on 21 Feb 1854, Pulaski County, Kentucky; he died 1 Jun 1932 in Shawnee, Bates County, Missouri. On 18 Mar 1875 in Pulaski Co, KY he married Sarah Ellen Inabnit, dau of William M Inabnit and Mary A Hargis.
3) Birth of son William Trotter Simpson on 21 Feb 1855, Line Creek, Pulaski, Kentucky; he died 20 March 1924 in Pulaski County, Kentucky. On 13 July 1876 in Pulaski County, KY he married Mary Elizabeth Rogers, dau of William Rogers and Cynthia Whitaker.
4) Birth of daughter Temperance Jane Simpson on 8 March 1857, Pulaski County, Kentucky and died 23 March 1897. On 20 Jan 1876 in Pulaski Co, KY she married Sampson Hawk, son of Gabriel Hawk and Martha Patseye Ashby.
5) Birth of daughter Mary Martha Simpson on 6 January 1859, Line Creek, Pulaski, Kentucky and died 28 Dec 1906 in Purdy, Barry, Missouri. On 19 Feb 1880 in Pulaski County, Kentucky she married William Mattison Barrett., son of John J Barrett and Mahala Combs.
6) Birth of son Shadrack Jackson Simpson on 26 August 1861, Pulaski County, Kentucky. He is age 19 on1880 census.
7) Birth of daughter Deliah C. Simpson, born Feb 14, 1862 and died July 4,1940, she was age 18 on 1880 census in Dallas, Pulaski County, Kentucky. On the 1910 census she is divorced and living in HH with father.
8) Birth of son Albert Lomax Simpson Jr, born 28 Dec 1863 in Dallas, Pulaski County, Kentucky; died 14 July 1953.
9) Birth of son James Elexander Simpson born 16 Dec 1867 Somerset, Pulaski, Kentucky; and died 7 March 1955 in Austin, Travis, Texas.
10) Birth of daughter Nancy Ellen Simpson (she is age 10 on 1880 census' birth month: March per 1900 census);
Nancy Ellen Simpson whom I think married William H Smith; and, a completely different person (Nancy J Simpson who married William R Nunnellley). On 30 July 1870 census, Mary Ellen Simpson was age 5/12 months. On 14 June 1880 cs, Mary Ellen Simpson was age 10. On 21 Feb 1889, a Nancy E Simpson married a William H Smith in Pulaski Co, KY. On 14 Jun 1900 cs, her birth date was listed as March 1873, (but would be March 1870 based on the 1870 census where she was 5 months old); and, lived in Rockcastle Co, KY. On 1910, 1920, & 1930 cs she lived in same county. Her husband died 26 Nov 1933 and death record said he was buried 27 Nov 1933 in Nichols Cemetery, Rockcastle Co, KY.
11) Birth of daughter: Surrelda Permelia Simpson in April 1871 and died 15 Oct 1933 in Fort Worth, Tarrant County, Texas. She married William R Harper 21 March 1889 in Pulaski County, Kentucky.
12) Birth of son: John Richard Simpson (10 Sep 1873 - 8 Jan 1964.
13) Birth of Matilda E Simpson (5 July 1876 - 2 Nov 1957).