"Guerilla Gardening" have you heard about it, done it, or noticed its positve effect on the landscape?

“Guerilla Gardening” is a somewhat radical practice of planting in abandoned lots, roadsides, and other places that are non-traditional gardening spaces- that benefit from individuals or groups deciding to add plantings and “bring life” back to an area. Have YOU heard about or done this? Also, what do you think of it as an “improvement”? (I’ve heard that it may help prevent Hive Collapse.), I’m totally there with it being an aesthetic and environmental act.