Is there a site to find a picture of, and issue date of US postage stamps?

A few blocks from where I live there’s a stamp/coin dealer, and I’ve gone there a few times to buy old uncanceled stamps for mailing. (As long as a stamp has never been used, it’s still good for postage, no matter how old.) Sometimes it’s fun to find a few interesting old stamps to use when writing letters, if I know the recipient will enjoy them. A business search for “stamp dealer” on Google maps will probably show a few places where you can buy old (canceled and uncanceled) stamps.

If you’re looking for information on a particular stamp, the most comprehensive stamp resource is probably the Scott catalogue. There’s probably a copy in the reference department of your local library.