Might your grandparents Clarence and Estelle be the parents of the former Mayor of St. Louis? Apparently, Clarence Harmon (Mayor 1997 - 2001) was born in St Louis in 1940. His father was a racetrack groomsman and a railroad cook. His mother, Estelle, was a nurse. Clarence Sr. was born 27 August 1901 per the US Social Security Death Index.
Clarence Sr. came to St Louis from Mississippi, as did Estelle Sadler, became a groom and later joined the railroad. He died in 1974. Estelle Harmon was a nurse at the old Homer G Phillips Hospital.
Clarence Jr had three wives, the first of whom he married in 1956 at age 17.
Hope this helps?