I have a kelloggs corn flakes all star card of tom seaver from the mets I a picture of him pitching the ball it is still in original packaging so it is in amazing condition I was wondering how much it was worth

Start with a Beckett's Baseball card value manual:
Baseball Cards Price Guides, Baseball Card Values | Beckett.com (http://www.beckett.com/price-guides/baseball)

Or visit a baseball card dealer.