An excellent guide for the new collector
My first "stamp catalogue" was a Postal Service Guide. I have graduated to the more expensive Scott Catalogue, but I still consider these books to be an excellent value. It is a great reference for identifying US stamps. You will find color photos of all stamps by Scott number (including some varieties) with the year of issue and a brief description. The catalogue values quoted here are useful when comparing the relative value of one stamp issue to another, but they do represent "retail" prices and you cannot expect to sell your stamps for the prices shown in the book. You will find even an old edition of this guide to be very useful. If you can pick up a recent edition of The Postal Guide in good condition at a fair price, don't hesitate to do so.