The rec center in North Berwick, Maine has multiple soccer fields adjacent to one another which makes for one nice big and flat flying field. There is a nice big parking lot if you have a plane that needs smooth ground and if you want to do some multirotor flying there is wonderful foliage in the fall and the rest of the year it is still awfully pretty. The playground would make some nice obstacles to race a mini quad around, if you like that sort of thing.
Disclaimer: Obtain air traffic control permission before flight in controlled airspace (Class B,C,D, or portion of E designated for an airport). Always check with local authorities before flight.