I've been thinking about this sort of thing for a while - guerrilla gardening - but have never actually done anything about it.
Seeing as I'll be leaving Reading in September to go to Uni, I wanted to do something like this before I leave.
There's a fountain that I've never seen work, attached to the side of St. Laurence's church near the marketplace. You can see it circled just under the top of the bus stand in the attached photo (courtesy of Wikipedia).
I woul say it's about a foot wide and a little longer in length. There is a hole in the bottom that drains into a drain I think, and the whole thing is about 25cm deep at the deepest point.
What sort of plants can you reccomend for a place like this? Ones that don't have too deep roots, but are still hardy (and perhaps fashionable, as apparantly the church is trying to appeal to a younger group of people).
I'd like to start this as soon as possible, and maybe get some help. But any and all advice is appreciated.

EDIT: Just had a quick scan around the internet for hardy, shallow-rooted plants. Do you think any of the following are appropriate?
Goldsturm (rudbeckia)
Geranium 'Jonson's Blue'
Thyme
Bearded Iris