* A cookbook produced by organisations or companies in your area. For example, my collection of books includes one by the Nashua (NH) Telegraph, which compiled the best recipes submitted by its readers, and another by Richland Washington Allied Arts Association, and a few gathered over the years from B&Bs.
* If your hosts are into genealogy, a gift certificate covering the cost of research at a local library or historical society.
* A locally-produced food item. Farmer's markets, small resturants, and smaller gourmet shops are good for finding unique items. (A local wine or beer from a micro-brewery, BBQ sauce, chutney/jam, herb or spice mix, etc.) My US friends always get a kick out of the unique flavours of crips/potato chips we get in the UK, just to live you an idea.
* Locally-produced soaps, lotions, etc.
* If they like antiques, maybe you could find a commerative paperweight or some other interesting item featuring the name or photo of your area.
* A CD by a local musician.
* Something made by a local craftsman or artist.