A brightly colored vending machine dispensing collectibles unexpectedly appeared inside the nerve center of the US military one day just before Christmas. And then, just a few weeks later, it was gone. The machine, which offers sealed, brightly patterned mystery boxes that could contain Pokémon card packs, sports cards, or signed athletic jerseys in exchange for a minimum of $80, wasn't in a casino or shopping mall, places where it is more commonly found; rather, it was sitting in the heart of