My best personal find was a spare oar on Oregon's Deschutes River. I think it had been caught in an eddy for a few days, because downstream I found a wrecked driftboat that hadn't made it thru Whitehorse rapids in very good shape.

When I was a Fishcop patrolling the pre-eruption Toutle and Kalama I "found" lots of things: lots of salmon hidden in bushes, snagging gear behind logs were some of the most prevalent; extra plunking rods on the Columbia ("He went to town for beer"), a personal record of 6 rods hidden in the woods, but all plunking, in front of a cabin on the Cowlitz (they were all pretty junkie) with no one at home, and one time a portable color TV which my patrol partner took home with him, cleaned up, and watched for several years.