WA State Discover Pass Required for Fort Worden State Park (and Fort Flagler if you camp there).  $10/day pass or $30/annual pass  -- strictly enforced.  (a ticket costs much more than a pass). -- plus its a good deal for a worthwhile government organization. 

Discover Pass easily obtainable online: http://www.discoverpass.wa.gov/

You can also buy it at the park, but only during their office hours. I strongly recommend buying it in advance, either online, at any other State Park, or at Retail Outlets who sell them (see online).  This will save you hassle if you come late Friday night.