Thelma Carmichael was the only child of Mr. and Mrs. S.D. Carmichael, an old family in the Tama, Iowa community. In 1905, S.D. Carmichael patented a playpen he designed for his only child. Called "Thelma's Screened Cariole," the playpen was manufactured by S.D. Carmichael, promoted through an illustrated booklet and sold both directly and through furniture stores. In 1948, Thelma Carmichael was still a well known citizen of Tama, serving as secretary-treasurer of the Tama County Historical Society of Iowa.