Great-grandson Charles Simonds said that he was a blacksmith and that his wife died before him. His death location and burial place is unknown.
Missouri, Marriage Records, 1805-2002. Anjalina Williams and William Stanley. 21 January 1872. Adair County. Image of original document available at Ancestry.com. Index-only record at FamilySearch.org: https://familysearch.org/ark:/61903/1:1:V28M-3PD
Oklahoma County Marriages, 1891-1959. Charles F. Stanley and Sarah E. White (son and daughter-in-law). 11 July 1894. Cleveland County. This record includes parents' names and ages and birthplaces of groom (23, Missouri) and bride (15, Arkansas). Parents of groom are listed as William Stanley and Angeline Williams. Parents of bride are listed as J. (sic) M. White and Caroline Perry. License dated 10 July 1894. Digital image of original document: https://familysearch.org/ark:/61903/1:1:VXLX-3TG
Texas Deaths, 1890-1976. "Charles Franklin Stanley" (son). 25 June 1946. Angelina County. Parents are named as "W. M. Stanley" and "Annie Williams". The middle initial of "M" may be an error - Charles' son was William Marion, named for each of his grandfathers, and he was the informant on the death certificate. Digital image of original death certificate: https://familysearch.org/ark:/61903/1:1:K396-7DG
It may be possible to confirm family relationships with William by comparing test results with other carriers of his Y-chromosome or his mother's mitochondrial DNA.
Y-chromosome DNA test-takers in his direct paternal line on WikiTree: