Saleen- Ok here's a few good spots to check out
Corbelt warm springs- about 15 miles east of Portland in the NE 1/4, sec. 27, T 1N, R 4E
I've done pretty good around hot springs with a metal detector, especially if they've been known about for quite some time. Check the surrounding areas where people may have changed clothes for rings and coins.
There was a portage area for immigrants from Bonnevile dam to the cascade locks. From what I understand it was a pretty sad story for those who had made it almost all the way here on the Oregon trail. Whatever they had left was pretty much stolen from them by unscrupulous persons controlling the area. May be a good area for artifacts.
Scarborough cache- I dunno about this one, kinda sketchy, but I'll give you the info I have on it and you can decide for yourself....
Southeast of Chinook, WA is a place called Scarborough Hill, named for Capt James Scarborough who took a 640 acre donation land claim there. He amassed quite a fortune, mostly in gold, exporting fish to the English. Died suddenly ( like most in these stories, LOL) and his cache has never been recovered.
"Fort Columbia cache" Oregon Journal, Feb. 14th 1932, sec. 5 p. 6
Lucile McDonald, "Washington's yesterdays" Binford's and Mort pub. Portland, OR 1953, pp.40-41
Letters of John McLoughlin, Oregon historical society, 1948, p 323.
Hult, Ruby El- Lost mines and treasures of the Pacific NW, 1954, "Scarborough Cache" pp 144-146
This one is definately true but I have no idea if its been recovered-The Johnson gold cache near Ilwaco on Baker's bay- Long story but well documented by those who were present, several eyewitnesses. I'll just give the references- 20,000 in gold slugs wrecked off the bar and salvaged by Capt. Johnson.
"Naming and early settlement of Ilwaco" Oregon historical quarterly, vol 47, (June 1946) p 181.
The Oregonian, March 30, 1936, p16. Item about Charles Bradt's discovery of a $5 gold piece on Johnson's claim.
L.R. Williams, "Our pacific county" Raymond, WA Herald 1930
For the full stories of both, see Ruby Hult's Lost mines and treasures of the Pacific NW, and the follow up, Treasure hunting NW. I see them both in the used bookstores every now and again. She was an excellent researcher and lists her sources, most of which concerning these two stories I have put down above.
The ghost town of New Era is just a couple miles south of Oregon City, on Market road off 99E. Several buildings and a mill should still be standing.
There are several fossil areas in Columbia county, OR just south and west of St.Helens. Mostly shells.
Agates are found a couple miles up Clear Creek, Columbia county, as well.