I am a resident of Boston who does not own or have access to private land, and does not own a car. I am trying to find a place in the Boston area where I can have a very small, private gathering outdoors, at night, with an open fire. (That is, a campfire or bonfire, as opposed to a wood or charcoal grill, like those pedastal grills in public parks.)

So far I am just completely frustrated, but there must be somewhere where one can go and just sit around a campfire without breaking the law. 

Can anyone help me out?