Cactus was a great project set up and run by Tony Credland and Glenn Orton back in 1989. It was essentially a mail art project based around fairly mass collaboration (well in pre-digital terms) . The idea was simple and elegant. Cactus sends out a call for entries around a simple brief, usually a single word or phrase. Then as a participant you send back multiples of your piece (usually around 100). Tony and Glenn then design and print up a lovely container and send you back one piece from everyone else.
I only have this one "Fuel to fight Fascism" but there were quite a few with some beautiful work, so if you ever find one - grab it.