I missed International Sunflower Guerrilla Gardening Day, which was May 1.
But I love the idea of guerrilla gardening, even if it's a bit...Criminal...But then again I did it a few times without knowing I did. I was growing plants in my dorm and because I didn't want to throw them away, and ended up planting them by a tree a little ways from my dorm building with my room mate.
Here are some links for you to check out. It's pretty awesome!
The Night Attack The Sunflower mob How to make Seed bombs Seed bombing in Haiti