at crescent city theres a few free spots along the smith river that are awesome, right near the redwoods.
the chetco river has awesome free camping at the miller bar. My favorite campsite from my summer on the road.
Oregon beaches are publicly owned and you can camp on the beach anywhere 1 mile away from a state park or town line. problem is these places are vitually inaccessible.
unfortunately throughout oregon you cannot camp on the beach or anywhere near the 101 that is free and easy. there are lots of cool campsites in the coast mountains, but still 15$ a night. every other dirt roads are private logging roads. not saying you couldn't camp there, you just may wake up to loud logging trucks or a trespassing ticket.
Another option is the hiker/biker campsites at the state parks. $5, no car parking.
One great spot is at ecola state park, I believe its called tillamook head. You have to hike a mile or two, but great campsites, two bunkhouses that sleep 4 each and community firepit. great sunset and ocean views from the bluff. Have to pay for state park, $5.
Luna Lake in the olympics is a good spot to go that is a real easy hike. Port Townsend is a great town.