Signese

Alright, I'll give it a shot: is it perhaps some sort of dedication offering to a Guanyin statue placed during the opening ceremony for 'Iron Ox Square'?

Along the right lines. More generally speaking, though, what is this item called, and where else might you find them?

It's a 锦旗 that you present as a way of saying thank you, here to a temple (ETA a particular bodhisattva statue strictly speaking) for a wish fulfilled. Hospitals/doctors get them too I'm pretty sure and think I've even seen them in govt offices being thanked for doing their job (though rare enough to merit comment I suppose).

That sums it up pretty well.