Hi. I'm not related to this family. You didn't mention your gg-grandmother's name, but I'm assuming this is the family in 1920:
1920 United States Federal Census about Winnifred Ferguson Name: Winnifred Ferguson [Winnifred Maurer] Age: 45 Birth Year: abt 1875 Birthplace: England Home in 1920: Forks, Clallam, Washington Race: White Gender: Female Immigration Year: 1890 Relation to Head of House: Wife Marital Status: Married Spouse's Name: Charles D Ferguson Father's Birthplace: England Mother's Birthplace: England Able to Read: Yes Able to Write: Yes Household Members: Name Age Charles D Ferguson 46b. 1874 Missouri, parents b. Missouri; driller, oil well Winnifred Ferguson 45 -wife- b. 1875 England, parents b. England Charles C Ferguson 8 -son- b. 1912 Canada (Am.Cit), fath b. Missouri, moth b. England
So, according to a tree on Ancestry, her name is Winifred Louisa Johnson, b. 1874 Wymondham, England.
There was a marriage license issued in 1919:
Date: Tuesday, November 11, 1919 Paper: Seattle Daily Times (Seattle, WA) Page: 27
"Marriage licenses...Charles D. Ferguson, legal, Seattle, and Winifred L. Johnson, legal, Seattle.
There is a newspaper notice of a divorce proceeding: Date: Wednesday, July 18, 1923 Paper: Seattle Daily Times (Seattle, WA) Page: 13
"In Divorce Court... Winifred Ferguson against C.D. Ferguson, cruelty.."
After that, it looks like Winifred married Charles Calhoun and, in 1943 she weds Charles Boyer:
Date: Wednesday, September 29, 1943 Paper: Seattle Daily Times (Seattle, WA) Page: 11
"Mrs. Winifred L. Calhoun became the bride of Mr. Charles R. Boyer on Saturday evening, September 11, in the Central Meth-... Mrs. Emma Jodell was the bridesmaid. Mr. Boyer's attendants were Mr. James Mires and Mr. Charles Ferguson.."
By 1 Aug 1945 Winifred asked for a divorce from Charles Boyer, citing "cruelty". ~ Wednesday, August 1, 1945 Location: Washington Paper: Seattle Daily Times
And then I guess her last husband was Louis Wilson.There is a small obit for Winifred:
Date: Monday, November 14, 1955 Paper: Seattle Daily Times (Seattle, WA) Page: 38
"WILSON-Winifred L., of 1222 1st Avenue, age 83 years. Beloved wife of Louis Wilson, Mother of Charles Ferguson of Seattle.."