One of my neighbors is British and he has a Guy Fawkes party every year. I always attend if I'm in town.
The party includes fireworks and a "bomb hunt" (golf balls) for the younger children. Almost everyone brings food and booze. In years past, I've taken veggie dishes that I like, except for one time when I brought spotted dick. This year, I thought I'd try to bring something that's traditional and "authentic," but I couldn't really find anything that seemed to fit the bill.
