ROCKFORD -- Rick Nielsen, longtime guitarist of Cheap Trick, clown prince of '70s power pop, co-owner of Piece pizzeria on North Avenue and arguably the most beloved human being in Rockford, is a hoarder. Not in the scary, clinical sense. In the scary, funny sense. He knows this. The other morning, Nielsen could be found poking around a drawer at the Burpee Museum of Natural History in Rockford, a drawer that contained his old shoes.