thanx for posting that link. Again confirmation that the old addage of us having to avoid all state parks in all states, is not correct.
I had to chuckle at some of the brochure: Did you notice that the coins you could keep are "coins in circulation" and/or "contemporary coins"? So technically wheaties and silver coins (which are no longer in circulation) you would have to turn in? Or could you keep them under the logic that *occasionally* a wheatie or silver roosie is still circulating? (as evidenced by coin-roll hunter hobbyists).
Or how about the lost & found verbage? You can hunt the wet sand beaches of all Washington state owned beaches, but must turn in all rings and valuables (except contemporary coins) to lost & found/police laws. Well, sure. This is true of ALL states, as EVERY state has always had lost & found laws on the books (to prevent you from keeping bundles of cash that fell out of a brinks armored car, or keeping the cow that wanders out through a hole in a farmer's fence, etc....).
And don't you love the 6" deep rule (with 2" long screwdriver to retreive with)? For sure there are rangers lurking about with rulers, to measure the depth of holes. And those same rangers are equipped with magnifying glasses to read the dates on your coins, to determine if they are "circulating" age range, or "antiquities". Anytime you fill one of those application cards out, a ranger is appointed to accompany you around to do those tasks, so be careful!
The only other thing I'd add, is that this brochure would only apply to state parks there, and not other levels/entities parks. Ie.: county land, city land, federal land, etc.... would be different (city & county land typically silent on the issue, ...... and best left that way

).