Very cool find, with the obvious decoration. I didnt know they made pottery like that, back east. It makes me want to find a piece or two. Anyway, there is probably more, wherever that one came from. Its probably very old, too.
What part of PA? You don't have to be specific... Just wondering because I'm from the Philly area. I'm no pottery expert but based on the more intricate design, I'd says it's late woodland... roughly 1000 to contact period. Someone who's more knowledgable can probably give you more details... but that's not me!