Growing food in rain gardens – it seems almost too obvious. But it isn’t done much, and somebody has gone to the trouble of studying it scientifically here. They planted “beetroot, onion, spinach, tomato and broad bean”. This sounds good, but it might be fun to experiment with trees and other perennial species. There are some tough plants out there that will tolerate wet and dry conditions better than your typical annual garden crops. Jerusalem artichoke comes to mind, which is a sort of invasive American prairie flower that produces enormous amounts of delicious potato-like tubers.