I know this a pretty random thing to be 'inspired' by but every time I'm on the train I often pass masses and masses of fields with randomly places circular hay bales. I find them quite interested, I mean what a cool way of harvesting I knows its probably not intentional but I think they look pretty funky just sitting there.
I think someone could create something pretty inventive using some of these, a bit of ambient media maybe?
While researching I haven't found anything that inspiring done with them apart from creating a massive corn maze. Sever Peterson and his wife Sharon decided to build mazes in their hometown of Shakopee, they even host a corn maze and fall festival.
I know its a little bit country, but I still think something cool could be created with the bales.