I live near Pittsburgh PA so anything with a sports-related theme sells well. Steelers wallhanging, table runners seem to bring in tons of money. Larger quilts in this area don't seem to do as well. We always joke that around here you could paint a rock black and gold and someone would buy it.
I think if you know your demographic (sports fans, art lovers, farmers, etc.) and make something with that in mind, people would support your worthy cause.
Good luck!