The back markings are Royal Sometuke Nippon. This backstamp identifies it as one that was made for the Japanese Domestic Market starting in 1906. Nellie LeynDyke was born in 1896, married in 1917, and died in 1984.
I don't know when Kirk's grandmother bought/received this but I know it has graced many Thanksgiving tables in our house for years. I guess I better put this on my to do list to learn more about.