I am not related. You'll need to obtain copy of SS 5 to see who Marvin Mitchell Mathis said his mother was. His father was William Jacob Mathis born TN 1872, widowed by 1900 and his sons, Wm H and Marvin M living with his married sister Nettie S Mathis Higgins as "borders" in Williamson Co instead of being listed with father who was listed with his parents. Unable to pinpoint record of W J Mathis first marriage, found about 5 possibilities.

Death certificate information on William H Mathis 1895 - 1961 married Effie Mae GRAVES abt 1923 when he was 28, they had Wm J Mathis abt 1925. Effie M b. TX abt 1901 single sister Fannie B Graves b. 1903 TX was residing with them in Montague Co 1930.

William J Mathis - Anna Lou Mitchell - Williamson Co TX
William J Mathis married Lou. A. Mitchell 11 Jan 1893 Williamson Co TX

MATHIS, WILLIAM H 18 Oct 1895 Williamson Co - 05 Jan 1961 Temple, Bell, Texas, lived in Stephenville returned to Stephenville same day for burial. Middle name not given, no WW I draft card found.

MATHIS, MARVIN M 14 Jul 1897 19 Dec 1989 92 79714 (Andrews, Andrews, TX) (none specified) Texas - Marvin Mitchell Mathis born 14 July 1897 Florence Texas registered WW I draft in Littlefield, Lamb Co naming father W J Mathis in Graham nearest relative 24 Aug 1918.

Artie Maple Mathis died 04 May 1970 Andrews Co TX age 62 married to Marvin M Mathis dtr of D. Thomas Van Zandt and Bertha Wise.

Marvin M Mathis
Gender: Male
Marriage Date: 14 Jan 1972
Estimated birth year: abt 1898
Age: 74
Spouse: Opal V Carr
Spouse gender: Female
Spouse Est Birth Year: abt 1904
Spouse Age: 68
Marriage County: Andrews
Marriage State: Texas

Source: Texas Marriage Index, 1966-2002

Name: Marvin M Mathis
Estimated birth year: abt 1898
Age: 85
Spouse's name: Willie G SLOAN [Mathis]
Spouse's Estimated Birth Year: abt 1903
Spouse's Age: 80
Divorce Date: 28 Feb 1983
Marriage Date: 20 Sep 1975
Number of Children: 0
County: Andrews
102522 MATHIS MARVIN M 77 SLOAN WILLIE G 72 20-Sep-1974 marriage date

Horace Franklin Mathis died Andrews Co 08 Dec 1989 ? son of William Jacob and Hattie Lowe.

https://beta.familysearch.org/s/collection/list

06 June 1900, Taylor City, Williamson County, Texas
William H "Matthews" born Apr 1864 Alabama married 1893 parents born GA occupation Preacher
Annie Mitchell "Matthews" born May 1870 TX bore 5 children all living father MS mother AL
Sallie B born Oct 1893
Bessie born Jan 1894
Will H born Apr 1896
Louise born Oct 1897
Edwin born Aug 1899

Albert B. Higgins married Nettie S. Matthis 10 Nov 1897 Williamson Co TX

04 June Pct 4, Williamson County, Texas
A Bert Higgins born Dec AR no age married 1898
Nettie Higgins age 31 born TN 1869 birth info listed as July 1888 record says bore 7 children all living
Loyd Solon / Solon Loyd Higgins born 15 Dec 1898 registered WW I draft Collingsworth Co
Wm H Mathis born Oct 1895 TX boarder says mother b. TN father TX
Marvin M Mathis born July 1897 TX boarder
William Osmond Higgins died 26 May 1962 Littlefield, Lamb, Texas age 61 father A. B. Higgins mother Nettie Mathis.

Nettie S. Higgins born 12 July 1868 Rutherford TN died 28 Sept 1933 Pct 4, Lamb TX wife of A B Higgins dtr of W H Mathis born Humboldt TN and Mary A Jordon born Murfresborough (sic) TN

W. H. Mathis married Mary A Jordon 08 June 1865 Gibson TN

17 Aug 1870 Rutherford Station, Dist 23, Gibson, TN
W H Mathis age 29 born TN farmer $950 real estate $500 personal wealth
Mary A Mathis age 31 born TN
Ellen Jane Mathis age 3 TN
Nety S Mathis age 2 TN
Hepsy C Mathis age 17 TN female

1880; Census Place: Abbotts, Gibson, Tennessee; Roll: 1255; Family History Film: 1255255; Page: 452A; Enumeration District: 45; .
W. H. Mathis 39 1841 TN NC NC
Mary Mathis 41 1839 TN SC SC
Elen Mathis 13 - Ellen J Mathis married Wm G Bright 14 Dec 1884 Williamson Co TX died in Austin 14 Nov 1936 born TN 12 May 1867 death certificate says father J M Mathis mother "Molly" Duke, buried Oakwood.
Nettie Mathis 11
Joseph Melton "Joe" Mathis 9 1871
William Jacob Mathis 8 1872
George Mathis 6 1874
Emma Mathis 3 1877

13 June 1900; Census Place: Justice Precinct 4, Williamson, Texas; Roll: T623_1679; Page: 10A; Enumeration District: 129.
William H Mathis Nov 1840 TN married 35 years father NC mother SC
Mary A Mathis Oct 1838 TN NC SC bore 6 children all living
William J Mathis May 1872 TN wdiowed born 10 May 1872 TN died Graham, Young Co 06 Feb 1964 son of W H Mathis mother listed as Elizabeth Jordon, buried Oak Grove Cemetery in Graham, Mrs. W J Mathis informant, lived in Graham 48 yrs.
Harris B Hoover Aug 1872 TX son in law married 1898
Emma Samantha Hoover 20 Nov 1876 Humbolt TN dtr died Florence, Williamson Co 15 June 1967, father William H Mathis, mother Mary A Jordon, buried Wesley Chapel in Florence.
Mary V Hoover Mar 1899 TX grand dtr
. . . Wm H and Mary Mathis residing with Harris B and Emma Hoover in Williamson Co 1910 and 5 Hoover children.

Miss Eunice S Mathis married Mr. H B Hoover 10 Apr 1898 Bell County TX
W. J. Matthews married Cassie Halmark 12 June 1892 Bell County TX
W. J. Mathews married Miss Nora Carter 13 Oct 1895 Bell County TX
Will Mathis married Birdie Dailey 18 Oct 1894 Hays County TX
J. W. Matthews age 19 married M A Duke no age listed 15 Aug 1893 Falls, Texas

1900; Census Place: Justice Precinct 4, Williamson, Texas; Roll: T623_1679; Page: 10A; Enumeration District: 129.
George Mathis Nov 1874 TN married 1899 living next to parents
Martha Mathis Nov 1880 TX England TX

J M Mathis married Mildie E Castles 23 Dec 1894 Bryan, Brazos Co TX

25 June 1900; Census Place: Temple Ward 1, Bell, Texas; Roll: T623_1610; Page: 21B; Enumeration District: 28.
Joe M Matthews July 1870 TN married Maud Motley 14 Jan 1900 Burnet County TX; Joseph Melton Mathis b. TN 27 Jul 1870 died Eagle Lake, Wharton Co 03 Aug 1948 says father was Wm J Mathis mother not mentioned.
Maude Matthews Nov 1875 TX died Whitney, Hill Co 01 May 1971 dtr of J T Motley and Sarah Frost
William Fowler Matthews Apr 1895 TX death certificate says Willie B Mathis born 28 Jul 1895 Bryan TX died in Abilene, Taylor Co 09 Feb 1955 father J M Mathis mother Ormilda Etta Castle
Alice Fern Matthews May 1897 TX

23 April 1910; Census Place: Justice, Andrews, Texas; Roll: T624_1527; Page: 5B; Enumeration District: 1; Image: 675.
dwelling 123
W J Matthews 37 TN 2nd marriage William J Mathis married Hattie B Lowe 06 Oct 1901 Williamson Co
Hattie LOWE Mathis 31 TX 1879 LA TN born 18 Jul 1878 TX died in Graham 24 Aug 1968 dtr of Thomas Levi Lowe and Mollie Elizabeth Jackson
Hiram Matthews 14
Marvin Matthews 12
Robert A Matthews 6 1904
George Howard Matthews 4 1906
Horace Frank Matthews 1 1909
dwelling 124
J M (Joseph Melton Mathis) Matthews 39 TN married 10 yrs said 1st marriage
Maud Matthews 35 TX VA VA 6 children
Fowler 15 1895 TX
Fern 12 1898 TX
Floyd 08 1902
Homer (Oscar written then crossed out) 06 1904 - Herman Castle Mathis died Abilene 25 May 1947 says born 16 Apr 1906 son of J M Mathis mother listed as Milda Etta Castle
Ward M 04 1906 died Corpus Christi, Nueces Co 13 Oct 1950 listed age of 46 yrs 3 mos 8 days mother Maude Motley
George 02 1908
Joseph Grady Mathis one month old 1910 died 24 Nov 1958 Wharton Co age 48 mother Motley

1920;Census Place: Justice Precinct 1, Young, Texas; Roll: T625_1854; Page: 4B; Enumeration District: 168; Image: 298.
William J Mathis 47
Hattie B Mathis 41
Robert A Mathis 16
George H Mathis 14
Horace F Mathis 10