There are several good quality quick service restaurants run by USC food service at the Village portion of USC campus at the corner of Jefferson and Hoover (area is open to the public during the daylight hours). Most places open for lunch and dinner but a few of them serve breakfast. It's a 5 minute walk from the Radisson.
The Radisson itself which is owned by USC has several decent sit down table service lunch and dinner options (they are also run by USC food service). There is also a pizza place, Whichwich, and Starbuck in the building next to Radisson which can take care of breakfast and lunch if you don't want to walk very far. You'll find all the usual fast food places within 2 or 3 blocks north and south on Figueroa Street from Radisson and USC campus if you are not picky.
Mercado la Paloma and Chichen Itza that Craig6z mentioned are on the other side of 110 freeway. It's a short walk from Radisson but some people may find it a bit intimating to deal with the crazy traffic at the corner of Exposition and Figueroa. But I echo his recommendations... they are both good places to try.
If you are here during a football weekend, there will also be lots of tailgating on campus... you can just walk in and try to make new friends
