Mostly they're found in processed foods. Right now, most fresh produce isn't GMO, though dairy, beef, chicken, and pork could be from animals that ate GMO feed, so check the labels. Some food ...

ProFerm contained 93 fungal compounds not found in cow's whey. The fungal proteins and compounds are unknown to science, have never been part of the human diet, and are by-products of the GMOs ...

For beef cattle and dairy cows ... Foods labeled "natural" can contain genetically modified (or engineered) corn, soy, sugar, canola oil, and other ingredients. "Natural" meat and poultry ...