The pilot stated it had been raining for a couple of days prior to the accident flight. He departed Clemson, South Carolina, on a visual flight rules flight and flew around the local area before landing at Seneca, South Carolina. The pilot stated he took a short break and departed Seneca enroute to Walhalla, South Carolina. The pilot stated he thought about not landing at Walhalla Airport since it has a grass strip and there had been allot of rain. He entered left traffic and decided to make a wheel landing. On touchdown the main landing gear collided with the wet, soft, soggy, grass runway, and the airplane nosed over inverted. The pilot stated, "I made an improper decision by not making at three point landing. I knew the grass was wet and the airplane would not have nosed over on touchdown in a three point attitude." The pilot further stated he did not experience any mechanical problems with the airplane before the accident.