On September 7, 2003, at 1900 central daylight time, a Piper PA-22, N615A, piloted by a private pilot, sustained substantial damage when it nosed over while attempting to land in a soybean field near Atwood, Illinois. Visual meteorological conditions prevailed at the time of the accident. The personal flight was operating under the provisions of 14 CFR Part 91 without a flight plan. The pilot and the passenger reported no injuries. The flight departed Tuscola Airport (K96), Tuscola, Illinois, at 1800. According to the pilot's written statement, the intended destination was Cooch Landing Area Airport (IL31), which is a private-use airport near Atwood, Illinois. The pilot reported he flew a traffic pattern above a soybean field that he mistakenly identified as the grass runway at IL31. The pilot stated he did not realize his mistake until the aircraft contacted the soybean crop just prior to touchdown. The pilot reported that it "was to late to go around so [he] attempted to land." During the landing attempt the airplane nosed over. The pilot stated that the soybean field in which the landing was made was approximately 1/2 mile from the accident location. The pilot stated that he was "fatigued" during the accident flight, which most likely contributed to his misidentification of the landing area. The pilot reported that the accident could have been prevented if he had verified the location of the runway while in the traffic pattern.