A lot of times the Churches on the Indian reservations will send out promotional material, usually highlighting an inspirational story, some historical event or a passage from the Bible. I got a letter one time with some sort of wood whistle, along with a story about a traditional musician from the tribe that used the echos from canyon walls in his music. I've also seen pennies and nickels attatched, along with other things. So I could easily see a replica of a widows mite being attatched to a letter solicitating donations.