Happy Hallowen!

ahh,,it's October,31st, isn't ? in our calender, there's no celebration, event, or else.But, in west, today is a Halloween day !
oh, actually, I'd love to celebrate it too. But, its not a culture in here, only a few people (know that event!) who celebrate it.
As I know from film,cartoon,comics and browsing internet, people who celebrate Halloween, give some candies or not to child.Trick or Treat. The children wear Halloween costume, like a ghost, a witch,a pumpkin (?), etc.


But, in my mind..
why're always on Halloween day, there's a pumpkin??? (>__<)