This is what the had to say in our local paper.
USDA said the unidentified farmer discovered the modified wheat when farm workers were trying to kill some wheat plants that popped up between harvests. The farmer used the herbicide glyphosate to kill the plants, but they did not die, prompting the tests at Oregon State to find out if the crops were genetically engineered to resist herbicides.
The tests confirmed that the plants were a strain developed by Monsanto to resist its Roundup Ready herbicides and were tested between 1998 and 2005. At the time Monsanto had applied to USDA for permission to develop the engineered wheat, but the company later pulled its application.