Gioco now serves brunch on Sundays, and is actively pursuing pre-game patrons:
Gioco
1312 S. Wabash Ave.
312-939-3870
Other breakfast places in the area -- that get pretty crowded on Sunday mornings--are Bongo Room and Orange.
None of these places is in spitting distance of Soldier Field, but many, many, many, many Bear fans walk from there and further to reach the park, so you'll be in good company.
Near Dearborn and Polk is a Bar Louie and Hackney's, altho you'll need to check for opening times. Further north on Dearborn is Custom House, which serves a not-inexpensive breakfast on Sundays in refined (altho casual dress is ok on Sunday morning) surroundings.
A little bit further north is the new Plymouth Court (401 S. Plymouth Ct.--just north of the library) which is now open Sunday mornings.
Search for more info about all of these places on the site.
"The fork with two prongs is in use in northern Europe. In England, they’re armed with a steel trident, a fork with three prongs. In France we have a fork with four prongs; it’s the height of civilization." Eugene Briffault (1846)