We went to the St. Marks Crab Festival a year or two ago. Did not opt for the crabs because they were (A) expensive and (B) not really "walking around food". There was an old guy there shucking oysters and selling them for dirt cheap. About the best oysters I've ever eaten.
Also: search out Alligator Point clams, either to cook yourself or a restaurant that serves them. They are excellent.
A person living in Tallahassee should really buy a skiff and catch their own seafood. (invite me). IMO, it's a great corner of the world to live, with the caveat that you will probably have much more success adapting to local customs than you will converting them to yours.
As already asked, where are you from? You need an answer because if your aren't them you are an "other".
For road trips, the Owl Cafe in Apalach and Liam's in Thomasville. +1 for Springcreek, too.
Also in Thomasville, Moonspin Pizza.
We've recently had a couple of very good quick casual meals at Old Town Cafe. Hadn't been there in years, but glad we decided to go back. Lofty Pursuits next door for ice cream after.
Angelette's for brunch or lunch.
Reangthai or Siam Sushi for Thai.
Zaxby's and WhatABurger for fast food.
Bruegger's for bagels.
Au Peche Mignon and Southern Seafood along with the farmers' market in Market Square.
I'll second Angelette's. The menu is mostly cajun/creole. They are also worth a try on Tuesday nights. They do only specials that aren't on their regular menu. I've had some very good dishes then.
Piggy's is my favorite barbecue.
I've also enjoyed Coosh's Bayou Rouge, a second cajun place. Had a very good dish of fried catfish smothered with crawfish etouffe there a few days ago.
My favorite white tablecloth restaurant is a la Provence, in Timberlane Center (www.aprovence.com) and for ethnic food, Sahara (Lebanese and Greek) on Lafayette Street, just off Apalachee Parkway. Locally favorite for burgers is the What-a-Burger chain, and with good reason.