According to the student pilot, he landed and taxied back on the east/west parallel taxiway for a subsequent departure on the same runway to the west. The taxiway traversed an open parking ramp and as the airplane transitioned onto the ramp, an unidentified marshaller directed the airplane down a north/south taxiway that circumnavigated hangars on the south side of the airport. According to the pilot, airplanes were parked along both sides with many parked across the double-yellow taxiway edge lines and into the taxiway object-free movement area. The student pilot said he endeavored to keep the nose wheel on the taxiway centerline as he'd been taught to maintain clearance. While taxiing, the left wing of the airplane contacted a parked airplane, pivoted around the contact point, and struck the tail with the turning propeller. The accident airplane sustained substantial damage to the left wing. The pilot reported that there were no mechanical deficiencies with the airplane that would have precluded normal operation. According to airport personnel, there was overwhelming response to a breakfast fly-in that morning that was neither NOTAMed nor anticipated, and overflow parking was not easily accommodated due to heavy rains and heavily soaked infield areas. Photos taken immediately after the accident depicted several airplanes parked over the double-yellow taxiway edge lines and into the taxiway object-free movement area.