Places to go near Boston?

My hubby and I are planning a one-week vacation mid-July to Boston. We plan to drive to neighboring states and check out the wonders of East coast. Does anyone know any FREE or INEXPENSIVE things to do/places to see in Boston and neighboring cities? (within 7 hour drive) I've found a few tourist-y sites, but I'm hoping to find some hidden gems like a hike along a secluded waterfall or something like that. Also any must-try restaurants??