This maybe another stupid question but what do the letters by the dates on coins mean like "d" or "s" and what are the most valueable. Thank you
these are the locations of the mint where they are made P=philadelphia S=san francisco d=denver these 3 are the most common nowadays
That totally depends on other factors. The elements that go to make up the value of a particular coin include its grade (condition); its date; its mint mark, if any; and its variety, if any. There is no mint mark which automatically makes a coin more or less valuable than any other. Dahlonega, Georgia (1831-1861). And don't forget a single "C" for Charlotte, NC, which minted gold coins from 1838-1861.
I believe that the only stupid question is the one that you already know the answer to, but ask it to see the response.
BTW - in other countries mint marks sometimes consist of letters, but many times "privy marks" are used. These are small markings such as cornocopias, torches, swords, or other figures, that usually appear near the date, but can exist anywhere on the coin. The use of privy marks began long before the practice of applying letters.