I have information regarding James E. (Elmore) Platt who married Elizabeth Grant in 1860. They may be the James and Elizabeth Platt who migrated to Jefferson County, Washington. James died prior to 1900, but Elizabeth lived on until September 1927. There is an obituary for her on file with the Jefferson County Genealogical Society, if I can get my hands on it. Elizabeth is the sister of my gr.gr.grandmother, Caroline Grant Davis. James Civil War pension record led me to search in Washington state where I found Elizabeth in 1900, 1910 and 1920, all in Jefferson County, Washington, widow. Don't have anything more at present to share, but thought it might be of interest to you.