The
Greenberg price guides are a good resource for identifying and establishing a value for Lionel trains. Just understand that the value of an item depends greatly on its condition, and the prices quoted in these price guides are ballpark prices that you could expect to *pay* for an item - a dealer is likely to pay anywhere from 10% to 50% of these prices if he is interested at all (he may pay more if he knows he can turn it around fast).
There is also a series of three books ("The Standard Catalog of Lionel Trains" series - Prewar, Postwar and modern) by David Doyle that have a lot of photos and some outdated pricing that can be helpful in identification.
If you post photos here, a lot of us can help in identifying the items and what you might expect to get for them.
Andy