If you're not a native Midwesterner and you find yourself out in that region, there are, in my opinion, two sources for pizza that are required for you to sample: Happy Joe's, and Casey's General Store.
Happy Joe's has been mentioned here before but Casey's is rather less well-known. It's certainly not the same tier as Happy Joe's... but it's remarkably good all the same, even more so considering where you obtain it: Casey's gas stations. Higher quality ingredients than you might expect, especially the pork-based ones (they'd better be, considering Casey's is Iowa-based); the pizza itself is on the saltier side.
Here's one I got a few months ago while I was visiting Des Moines - half sausage, half Canadian bacon:
post edited by Ketteract - 2013/01/29 09:45:19