I collect the coin and have been keeping them in a plastic coin cap individually. But some time I take them out to handle them. I've noticed that my Silver Eagle coins 1 oz 999 silver is turning color to diet pills online yellow and black... why is this? And how do I clean them ? thank you.

I have a 1934 10 dollar bill, An "A" Note with Paper money shop drugs collecting. "will pay to the bearer on demand".  Is is worth anything? I also have a lot of silver coins and wheat pennies I've collected over the years but am most curious about the 10. Help!

I know pre 1964 silver coin value are 90% silver. How do coin shops figure out how much to sell it for at $100.00 face value at $15.00 per ounce.