She is on the 1920 census and husband died in 1925,listed as a widow on his death cert. She is listed on findagrave died in 1923, but I did not find a Tx. death cert for her, under the name of Culwell, Colwell, or Calwell, and I checked from 1920 to 1925.
I checked with Mary, Polly, and just her initials. I wonder if she died in another state, and was buried in Texas.

Maybe you will have better luck than I did. You can check it here. Good luck.

https://familysearch.org/search