travisl found We Mean Business (Traditional Cache)
Good thing I parked when I did. If I'd continued on through the tunnel like I was about to, I've got no idea how I'd get back here. I was going to leave cards for other folks, but when I saw the envelope marked ''Portland Cache Machine'', I knew we could each take one. Classy; thanks.
Neat area. Too bad we didn't have time to sit and vegetate on sturgeon, nor perform surgery on vegetables.