Thank you again everyone. Appreciate hearing everyone's thoughts and input.
John and Sarah married in 1897 and all 4 parents were alive at the time. If I were to guess as to whose image was on their pins, I'd say it was Sarah's grandmother who died in 1901.
With everyone's help, I can now say that our family does have a photo that, for me, bears some historical significance. This is the only mourning photo we have in the family. Pictures of deceased, yes. But up till now no mourning photo. Happy I am, indeed.
Thanks again!