The pilot had recently purchased the experimental amateur-built airplane. He was flying with a flight instructor to gain flight experience in the airplane. The pilot reported that he had made a normal left hand pattern and approach to the runway. During the flare, he attempted to maneuver the airplane to the right using aileron and right rudder inputs. The pilot said that the rudder would not move and he focused on the rudder problem. The airplane rolled out on the runway in a "sideways motion," the nose landing gear collapsed, and the airplane came to rest nose down on the runway. After exiting the airplane, the pilot and instructor observed an auxiliary electrical plug had lodged behind the right rudder pedal and had jammed it. The pilot indicated that there were no airplane mechanical malfunctions. The flight instructor's safety recommendation, in part, stated, "This could have been prevented by stowing all movable items before and during flight to keep them away from the flight controls."