Re: Really excited to visit the other Columbia!
Groucho's is only an institution, nothing doing food-wise. If you want a huge lunch with local flavor, go to a BBQ joint (Docs or Palmetto Pig). If you want a burger on campus, go to Pawleys front porch. Blue Cactus is good, but not Southern. Thirsty fellow is always a good time, at any hour. Lizard's Thicket has your basic meat and three if that's your thing.
For dinner, try Blue Marlin for basic Southern coastal, Hunter-Gatherer, or for a fun crowd there's always Flying Saucer.
I love Mizzou fans. Hope you have a blast.
edit - I second: Rockaways (best value, if you can find it) and California Dreamin (Just because it looks cool, honey croissant and its next to the liquor store) Also, if you're up early enough to get breakfast, you're doing it wrong. If you have to eat early, Waffle House or Bojangles.