What was the name of your grandfather and any brothers or sisters? I found a a John R. Sims and wife Rebecca in 1900 and 1910 but both in Cumberland Co. TN. Then in 1920 John and children from TN with a younger wife Nancy and more chldren born in AR in Van Buren County. If the names of children that you have match the census then I will send you the information on the censuses. If this is your John and Rebecca then her maiden name might be Dyer.