Love the idea of planting food in abandoned lots; some cities do have such programs. Planting on municipal grounds without permission though would likely be unwelcome. A much more productive idea would be to partner with the municipal authority and establish a small plot on which food to be grown to supply a shelter or food bank. Costs may ultimately go down for the city who often have to feed the homeless or fund or supply the shelters, so this type of arrangement is a win-win for all concerned. Getting some troubled youth, homeless, or other target group as additional garden help teaches responsibility and skills they can use the rest of their lives. IT AIN'T EASY but it's ultimately rewarding.