Joe, Is that a date right under the horizontal base of the "wheat?" Looks like an "A" at the top. With that shape of the intersecting lines....any chance it is "Masonic Lodge" type of thing? Just a wild guess though.
I have seen all sorts of odds and ends put in place of the Bear coins. The previous owner might have had some sort of connection to this and thats why. Often times you see something with the date on it like a coin etc.
I have also seen all sorts of holes people have drilled in risers. For the life of me I can't understand either.