ANAHEIM, Calif. -- The items arrive by the thousands, borne on furniture dollies, in Radio Flyer wagons or nestled carefully in owners' arms. The hodgepodge parade consists of paintings, teapots, firearms, mannequins decked out in military uniforms and more. Much more.Grade-schoolers have show-and-tell for their treasures. The adult counterpart is PBS' "Antiques Roadshow," which has become an institution as it approaches its 18th season and holds fast as public television's highest-rated series.That's right: It's No. 1. Not glamorous, romantic "Downton Abbey," but homespun and earnest "Antiques Roadshow," where Civil War firearms, Tiffany lamps and autographed baseball cards are the stars. Even Kevin Bacon watches it, which he admits in an on-air PBS promo.