That is the mark of Thomas R Markusen of Kendall, New York, as shown in Rainwater's Encyclopedia of American Silver Manufacturers (Fifth Edition) without any further information. He must have also worked in silver. Addition - His name is followed by an asterisk, denoting his membership in the Society of American Silversmiths.
You're welcome! I have a decent "visual memory" and knew right away that I'd seen that mark from my many hours of trolling through Rainwater, even though I never needed that particular mark before. If you google him, there are a fair number of museum listings of his work.
Been there,done that.....White House Collection & The Vatican!!!...I think I will hold on to these & pass them on!!