Coin silver mug - J Conning

This mug was given to my Mother about 45 years ago by an old spinster lady in Memphis, TN. I looked up some information on the internet and found that by the markings on the bottom that it was made by J Conning of Mobile AL.The mug has an inspription on it that reads "B. F. S. to Rev. Wm. Spence". The neighbor lady's name wasn't Spence. I looked up the name on the internet and found a Rev. Wm. Spence that apparently came to the US in the early 1900's from Canada. His son, Hartzell Spence, wrote a book about his life that was later turned into an academy nominated movie. It was called "One Foot In Heaven". Now wouldn't it be something if this mug had originally been given to THAT Rev. Spence.