SandraHill,
First, nonsense! There's no such thing as "too many" coins! Are the coins already separated into logical groups, or just random? How old are they? Do not sell them to an untrusted stranger!
Second, I would follow the advice of Morpheus. I would separate them by types. Separate the Roosevelt dimes and Washington quarters dated 1965 and older, and Kennedy Halves 1971 and older. Separate the Jefferson nickels with a mintmark on the back (like CBC says). Separate any coins older than 1965 that look "new" carefully, and put them into plastic coin flips for protection.
Next, stop there. I would get someone who knows something about 20th century coins to help you. It sounds like you have a long ways to go to get that far.
By the way, this is probably not the correct forum for this topic, it may get moved.
Good luck!