Something that seems to work well and is pretty low work is cutouts that are placed on a board or windows with the donators name.
Also pennies have been pretty well phased out in Canada (not sure about Chicago) but banks still take them. Lot of people who wold be glad to get rid of their pennies without being sneered at
Perhaps a pain to roll, but a bank or business with a coin rolling machine might do it free for a good cause, or you could have a penny rolling contest at the end of the drive.
Helen