A quick google of Decatur/Mt. Davidson reveals that my and Sitton's kindergarten teacher must have been Miss Decatur, not Mrs.
George Decatur was a Western Union clerk and also Director of the YMCA. He was instrumental in organizing the first Easter sunrise service on the mount in 1923, and raised $1,000 to have a wooden cross erected. A sturdier stone cross was erected in 1934, designed by George Kellham and Henry Brunnier. The construction contractors for the cross were the Monson Brothers. Mr. Decatur was also very much involved in this endeavor.
www.mtdavidson.org/mount_davidson_cross has the whole story and a photo of Mr. Decatur standing with the Monson Brothers. The Encyclopedia of San Francisco site (Mt. Davidson page)also has the story, and Mr. Decatur is mentioned in the last two paragraphs.
How nice to have had a Jefferson kindergarten teacher whose Dad was such a passionate and committed SF citizen. She must have been very proud...