While it can be time consuming, I always check my bills to see if they are “star” bills. When bills are printed, it is not uncommon to have one in a set that is spoiled or unacceptable for circulation. It is usually cut out of the page of bills and a “star” bill is substituted as a replacement banknote.
Star bills have an asterisk(*) at the end of the serial number.
Replacement banknote – Wikipedia
Here is a typical star note (image from Wikipedia)
More from the internet:
What’s In Your Wallet? 15 Bills Worth Way More Than Face Value
Star notes are collectible and you can check eBay for current values.
Other bills, like Silver Certificates and Gold Certificates, and error bills are more unusual and note often found in change from the grocery store – but don’t let this stop you from looking! If you find a bill that seems “off”, google it to see if it may be valuable. You never know!
I had a friend who owned a small coffee shop, and he told me that a kid came in and paid for a lot of candy with a bunch of coins – at the time he didn’t think anything of it, but when he went through the till at closing, he realized they were all old silver coins. While he never saw that kid again, he felt bad – because the young man did not know what he was buying candy with.
Bills with very rare errors, like mismatched serial numbers, alignment errors, and more — have a tremendous premium at resale. Look at these on eBay!
Even if you are not in a cash business, I would strongly recommend that you take a closer look at the bills in your wallet on a regular basis — because you never know what you may find!
Should you find some unusual or rare bills, put them aside, and try to find their value with a google search, etc. Sometimes a coin shop will give you a wholesale value offer on them, especially if you don’t want to go through the hassle of selling on eBay!