There isn't supposed to be any GMO wheat grown in the US for commercial production. There is some testing authorized though.
Unless you buy all organic foods, you are probably eating all sorts of other things with GMO DNA though. Almost all the corn and soybeans grown in the US are GMO. Think about how many products have corn-derived sugar and/or soy-derived oil in them. However, by the time they get done with all the processing, there probably isn't a whole lot of GMO DNA remaining in sugar or oil products. Cornmeal and corn and soy flour are a different story. They are almost certainly ripe with GMO DNA. Plenty of other vegetable crops may be GMO too, and plenty of animals are fed GMO grains.
According to the article, the GMO wheat found was a glyphosate-resistant variety. Farmers would like such a wheat because they could use glyphosate-based weed killers (believed to be very safe) to control weeds without killing the wheat. Sometimes glyphosate-resistant crops are called "Round-up ready" after the week-killer with the same name.
GMO crops have also been used to increase crop yields and help them to grow where they couldn't grow well previously. GMO has been able to increase disease and pest resistance, increase drought resistance, require less fertilizer, and increasing plant yield. It's good for profit and also good for places in the world where they can't grow enough food.
I would note that the article you cited is from an activist website, and is likely a bit alarmist. I bet if you search you can find other articles from news organizations that aren't quite as scary.