My mother grew up in a couple of towns not too far outside of Boston. Here is her recipe for Boston Baked Beans...

1 lb. pea (navy) beans
1/2 lb. salt pork
1 teaspoon salt
1/4 teaspoon pepper
4 tablespoons brown sugar
1/2 cup dark molasses
1 teaspoon dry mustard
4 tablespoons ketchup
1 minced onion
2 to 2 1/2 cups boiling water
2 tablespoons pickle relish
vegetable oil

Wash beans. Take out any bad beans, put good beans in a dish of water, cover, and soak overnight. (To ensure there is room for the beans to rehydrate, use a large bowl and cover the beans with an extra 2 or 3 inches of water.) Next day, take out any remaining bad beans. Parboil beans until skins begin to burst. Drain the water. Add all other ingredients to beans except salt pork. Cut salt pork into 1/4 inch cubes. Put beans and salt pork in baking dish or bean pot (bean pot is best), alternating beans and salt pork in layers, with salt pork on bottom and top. Put in cold oven. Turn oven on to 350 degrees Fahrenheit and cook approximately 5 hours, adding water and vegetable oil as necessary to keep beans from drying.