I'm originally from IA, now live in the Omaha area...I am a huge fan of the downtown farmers market in DM...I think it's waaayyy better than any out here in Omaha, so I would definitely hit that up if you get a chance. One way I have found to get good deals on produce out here (would probably work in IA too) is to talk to some produce managers at stores...I have recently gotten to know the one at a Hy-Vee by where I live, and he basically just told me to get ahold of him anytime I need produce (usually have to buy by the box or something though).
Anyways, those are my two cents. Good luck! and Go Hawks!!