Hi Roddy:
I would look for already established gardens and see if there's some kind of network in LA. There's bound to be one. They can help hook you up with volunteers and perhaps even act as oversight for you to get some funding. I know there are organizations in several cities that do this, including in Phoenix.
You could truly wow people by installing low
water use veggie gardens in LA. I know that in Phoenix, the biggest barrier to community gardens is paying for the water. Many community gardens end up becoming "degenerative" users of water and often they shut down when they can't pay. Search out some
local experts (Ron Finley?) in your area.