I saw that the other day, and it was the inspiration for today's topic. I don't normally eat breakfast cereals, but I will buy the GMO free Cheerios, and express my desire for more similar products to General Mills.
When I really started looking at GMOs, I was shocked at how difficult it is to buy things that haven't been modified. I used to think it was mostly ingredients found in processed foods, but like you discovered, it's flour, sugar and many other things that we use to make things from scratch. Even tomatoes, now. Labeling is desperately needed, but every time an initiative goes on a state ballot, Monsanto pours massive amounts of money into that state to deceive the public. So far they have been successful in defeating all measures.
Monsanto is the perfect example of how corrupt our government is in DC. Money buys a lot of politicians, and the masses who vote just keep sending the same crooks back because they don't pay attention to what's going on.
Look for a movie called The World According to Monsanto. It's a documentary, and can be found online. I watched it on YouTube, so it's probably still there.