I agree with the collards, but I doubt most of the perennials can get
big enough soon enough, and I think it might be hard to find some of
the weedier ones in the city -- unless you can ask your local
freecyclers if you can dig up established plants.
Since the need is to cover up the soon-to-be-condemned crumbling
foundation ASAP with greenery and to provide a substrate for
inevitable urination this summer, I'd go with tomato, squash and
collard plants. You can buy seedlings (from 6-packs to 1-gallon) in
any local nursery now and, assuming your soil is adequate, have them
reach a pretty good size within a month.
Whatever you plant, it won't be able to withstand a lot of abuse
until the roots get going (at least a couple weeks or over a foot or
so high), so you will have to coddle them in what sounds like a
difficult situation at first.