Her maiden name was Bookout, she was first married to Joseph Cornelison, and then later to a Mr. Fairchild.
1) "United States Census, 1880," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:MNWX-ZKX), Mary Backaut in entry for John A and Rebeca C Backaut, 1880; citing enumeration district ED 102, sheet 520D [War Eagle, Madison, Arkansas];
2) "Oregon, County Marriages, 1851-1975", database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:F8WG-6J7), J. M. Cornelison and Mary Bookout, 1891 [most, if not all, of Mary's family had moved back to Oregon];
3) "United States Census, 1900," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:M36L-8P2), Mary P Cornlison in household of Joe M Cornlison, War Eagle Township Huntsville town, Madison, Arkansas;
4) "United States Census, 1910," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:MKVD-5J3), Mary Cornelison in household of Joseph M Cornelison, War Eagle, Madison, Arkansas;
5) "United States Census, 1920," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:M48G-MZD), Mary P Corneilson in household of Joseph M Corneilson, Elgin, Union, Oregon;
6) "United States Census, 1930," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:XCQG-Y7W), Mollie Cornelison, Wapato, Yakima, Washington [she has listed herself as widowed, but so has her husband--they are either separated or divorced];
7) "Washington, County Marriages, 1855-2008," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:QPMT-H8G), Mollie Bookout a d J M Cornelison in entry for Omer A Cornelison and Icel M Overturf, 14 Jul 1928, Walla Walla, Walla Walla, Washington;
8) "Washington, County Marriages, 1855-2008," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:QPMT-ZYJL : 28 November 2018), Mary Bookout and Joe Cornelison in entry for Joe O Pratt and Ora E Cornelison, 9 Jul 1929, Walla Walla, Walla Walla, Washington;
9) "Washington, County Marriages, 1855-2008," database, FamilySearch(https://familysearch.org/ark:/61903/1:1:QPMV-SH3M), Mary Bookout and J M Cornelison in entry for T R Cornelison and Doris Lyon, 4 Jun 1930, Wenatchee, Chelan, Washington;
10) "Washington, County Marriages, 1855-2008," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:QPMT-K2PX : 28 November 2018), Mollie Bookout in entry for Wesley C Garred and Ruth V Cornelison, 18 Oct 1930, Walla Walla, Walla Walla, Washington;
11) "Washington Death Certificates, 1907-1960," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:N3TT-ZQP), Mollie Bookout and Joe Cornelison in entry for Elmer Cornelison, 08 Sep 1945; citing Yakima, Yakima, Washington;
12) "Washington Death Index, 1965-2014," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:QLW9-8CK1), Mary Fairchild, 21 Dec 1971, Washington;
13) Mary Fairchild in the U.S., Social Security Death Index, 1935-2014 (Sunnyside, Yakima, WA) [birth and death dates; birth date matches the 1900 census record].