Pull any bill out of your wallet. See the dark green numbers on the top-left and top-right corners? Those are serial numbers, and some are more rare than others. If you happen to have paper money with ...

Experts say rare 'radar' banknotes with mirrored serial numbers can command a premium, especially when paired with higher denominations or unique repeating patterns ...

Are you overlooking any rare “radar” banknotes in your wallet or purse?

Collectors' love for specific years and digits on bills and the surge in metals prices means these coins and dollars may be worth more than their face value. Here's what to look for.