The clerk's filing endorsement on the marriage bond, filed 8 Nov 1875 by A. J. Cox. It reads "James B. Wyatt and Louisa Casey," but that's the clerk's later reading of the bond's handwritten W. — the bond itself and the license (below) both read "James W." See Sources.
1880 U.S. Census, Washington Co., Virginia
Wife in the first household on the page, “Louisa,” age 25, keeping house; born in Virginia, as were both her parents. United States Census, 1880 — Washington County, Virginia: Washington. Census. See Sources.
1900 U.S. Census, Washington Co., Virginia
1900: “Louisa E.,” wife, born June 1854 (age 45) in Virginia, both parents Virginia; married 24 years, mother of 12, all 12 living. 12th Census of Population 1900: Washington. Census 1900. See Sources.
1910 U.S. Census, Washington Co., Virginia
1910: “Louisa E.,” wife, mother of 13 children, all 13 living, with seven still at home. United States Census, 1910 — Washington County, Virginia: Washington. See Sources.
Marriage license wrapper No. 637, 1875
The license's own filing wrapper: No. 637, "James W. Wyatt and Louisa Casey," issued November 3, 1875, entered at page 136 of the marriage register — W. again.
Marriage bond, Sullivan Co., Tennessee, 1875
The marriage bond itself, dated 3 Nov 1875: "James W. Wyatt" with sureties R. R. Mumpower and M. L. York, a $1,250 penalty, "to Louisa Casey of the County of Washington, Va." The groom's own line reads "James W. × his mark Wyatt" — he signed with an X, so the clerk wrote his name from what he said aloud. (The 1910 census likewise shows him able to read but not write.)
Marriage license, Sullivan Co., Tennessee, 1875
Their marriage license, issued at Blountville by clerk A. J. Cox on 3 Nov 1875 and solemnized the same day by George R. McClellan, J.P. — confirming the register's marriage date and place. It names the groom "James W. Wyatt" — the initial is identical to the W in "Wyatt" beside it. [Marriage Records]: Sullivan. Marriage Records 1863–1950.