This is a good article and a short one in Positive.News, about Ron Finley, a guerilla gardener in Los Angeles.
You may have already seen the 11-minute TED Talk he did, if not I highly recommend it and it can be found here [3 million views]:
Ron Finley plants vegetable gardens in South Central LA — in abandoned lots, traffic medians, along the curbs. Why? For fun, for defiance, for beauty and to offer some alternative to fast food in a community where “the drive-thrus are killing more people than the drive-bys.”
A victory for urban gardeners! Thanks in part to a petition introduced by Ron Finley, Los Angeles has legalized curbside gardens for community use.