Oklahoma, much like Iowa State, is not a corn. They're not an insect. They're not even a disease.
Oklahoma is dirt.
Now at first this might seem like an insult but it's not. It's meant with the utmost respect for the Oklahoma Sooners football program. It was dirt that lead Oklahoma to build one of college football's best programs. Sooner greatness was born out of the slight felt by Oklahomans because of how they were portrayed in John Steinbeck's book 'The Grapes of Wrath'. The book portrayed the Okies of the dirty thirties and the Great Depression (and if'n you ain't read it, ya should).
Oklahoma felt that by having a great football team that they could restore the pride of their state. Thus came the greatness that was Bennie Owen, Bud Wilkson, Barry Switzer, and now Bob Stoops.
Those could all be the reasons that I choose dirt to represent Oklahoma. Or it could be a reference to the program they're running. From Barry Switzer forced to resign because of repeated NCAA violations to Bob Stoops vacating victories due to a lack of oversight, it's something that is as basic to the Sooner program as great running backs.
You choose which one fits best.
Other Corns of the Big 12