Dates on the coins.....
Naw, there aren't a lot of D mint coins out here. Mostly S mint, which is actually a good thing since they tend to produce low mintages. The Buffalo is the most valuable of the lot...
Wheats: 1912, 26, 41s, 44s
Baffalo: 1919s ($30-40)
Mercs: 1918s, 35s, 43s
Quarter: 1944s
Fresh water is better than salt for any kind of coin, small cents are better in water than land, and silvers are better on land than in water... at least that my experience.
HH!