According to the website care2.com, Walmart, "is set to sell a new form of genetically-engineered (GE) sweet corn as early as this summer. Monsanto’s Bt sweet corn contains three GE traits that have never before been consumed directly by humans, and have not been subjected to thorough safety testing. There will be no labeling whatsoever indicating that the corn is a genetically modified organism."
They problem is the corn will not be labeled as a genetically engineered. There will be no way for you to tell . If this isn't a reason to grow your own, or support your local farmers market then what is? We have talked before how the interest in growing your own food is partially fueled by food safety. How can you feel safe eating the food from the grocery store? Walmart could make a decision to at least label this stuff, but they won't.
If you want to take control of your food supply this year here is a great primer from Farmer Fred for the beginning gardener.