With some simple testing you'll find these aren't. If I remember right this is tin plating. Also you can google image search circuit board tin plate.
Take care
Andrew
Looks like tin plate to me, one way you could test is by using a hot air gun, tin is easily melted and you see when the solder melts. Silver plate usually have a more matte finish.
Another way is to dissolve some with nitric acid and test for silver with some chloride and look for the white precipitate.
But the best way to test silver is Schwerter's solution.
http://goldrefiningwiki.com/mediawiki/index.php/Schwerter%27s_solution
Don't be discouraged as there is silver plate out there. There is also gold and pgm traces. But you got to test, test, and test! Some of my favorite traces were pd, pt. Its out there you just have research and find it.
Andrew