I do this from time to time and have an idea of what's special and hard to find elsewhere. Here are some easy calls, many pizza-friendly, most of which won't need refrigeration. Hope the driver doesn't mind the smell of garlic and cured meats.
Riviera -- as much salume as the folks can carry, especially the sopressatta -- unmatched in my experience, better than respected NY, SF, Seattle producers
Paulina Market -- landjaeger, hot lamb sticks
Calumet Fisheries -- smoked chubs, salmon, whitefish
Vietnamese/Thai naem sausage -- any Argyle-area crocer (consider also whether you want good South or Southeast Asian dry goods from Devon or Argyle that might be tough to find where you are -- good fish sauce, shrimp paste, rice noodles, whatever) Grab a Vietnamese pate while you're at it, from Ba Le. They make good naem also.
Bosnian/Serbo-Croatian cured meats from Devon Market, close enough to Romanian (which I endorse -- get some chopped liver in addition to the sausages)
Try the cured, smoked beef from
http://www.harczaksausage.com/index.php (local Serbian producer), which should be on hand at Devon as well as other area grocers
Ditto on the Bende stuff
Real pierogi and kolacky -- I like Delightful Pastries, but Kasia's are good and widely available
And as long as someone is visiting an Eastern European or German market, grab some jars of Polish pickles, sour cherries in compote, etc.
Chicago hot links are also pretty special and unique. Peoria Packing's are good. These are uncured and sold frozen.
Middle Eastern sweets travel well -- Nazareth Sweets is very good.
Like the Chicago Kimchee call too.
And don't forget the local beer -- I'd take Two-Hearted, Daisy Cutter, Alpha King, Matilda, etc. any day.