What's The Value Of Used Coins Dating Back From 1990 And Older?

A good place to start would be with this site here. It has reletively comprehensive tables and charts containing information that gives approxtimate valuations on US coins.

As far as I know though, any recent-ish coins that have been used or circulated, would only be worth their face value. It would only be coins in mint condition or "collectors" coins that would have increased value.

If you want to know the value of any kind of coins, you need to have a reputable dealer look at it. The condition of a coin is very important, and as an amateur, your judgment may not suffice.