Special Brexit 50p coins are selling for up to £15,000 online due to their rarity - so check your change to see if you're carrying around a goldmine in your wallet.
The Royal Mint released these 50ps to mark the official Brexit date of January 31, 2020. On one side they have the Queen's head, and on the other an engraving saying 'Peace, prosperity and friendship with all nations'.
Around 10million of the coins were released, but many ended up in the hands of collectors, driving up the price of those remaining.
Astonishingly, two of these 50ps recently sold on eBay for £15,000 each, 30,000x more than their face value.
Some are optimistically on sale for up to £50,000 on the auction website.
Have you bought or sold a rare coin? Email sam.barker@reachplc.com.
Other examples of the coins have sold this year for between £3,500 and £10,000.
But if you do find you own one of the special 50ps, be aware that you may be undercut when you try to sell it.
Some eBay sellers are listing the Brexit 50ps for a more wallet-friendly price of £1.35 - perhaps not realising the value of what they have.
ChangeChecker expert Alexandra Fiddons previously told The Mirror: "The 50p was teased for a long while before the UK's official exit from the European Union and when it was officially released into circulation, people were eager to snap them up for their own collections.
"This coin marks an incredibly significant moment in British history and it's possible that people who aren't usually interested in the hobby, may have been tempted to secure this 50p to commemorate the event forever."
Speaking on what makes a coin 'rare', she said: "Sometimes we see coins listed for prices well above their face value on the secondary market.
"Sometimes this is driven by low mintage figures, meaning there are fewer coins for people to collect, but it can also be driven by the popularity of the theme."
There is one other version of the Brexit 50p that is even rarer - and is worth much more than the 10 million in circulation.
Some of the Brexit 50p were minted two years ago with the date of October 31, 2019 - the original Brexit date, which ended up being missed.
Then-chancellor Sajid Javid had asked for three million of the coins to be made ready for this date, with another seven million to follow later in the year.
Around one million of the coins were made before the government realised it would miss the October 2019 Brexit date.
While most of the coins were melted down by the Royal Mint, some made it into the wider world.
If you are tempted to buy any second-hand coins from eBay, beware of fakes circulating.
An Olympics 50p coin with an error in its design recently sold for £420 on eBay after sparking a huge bidding war - but an expert says it could be a fake.
The eBay listing is supposedly for a rare version of the aquatics 50p that formed part of the London 2012 Olympic Games series.
The Royal Mint redesigned this 50p shortly before its release, so there are fewer water lines crossing the swimmer's face.
But a few of the coins were accidentally minted with the old design, with the lines still visible across the swimmer’s face.
The eBay listing says the seller is flogging one of these rare error coins, but Colin Bellamy, owner of the Coin Hunter website, told The Mirror that he doesn't believe the coin listed is genuine.
If you're bidding online, the Royal Mint encourages you to do your research first.
"If you are buying a coin on the secondary market we would recommend doing some research first, and there are a lot of useful resources on The Royal Mint’s website to help ensure collectors pay a fair price," a statement said.
Think you may be sitting on a fortune? See our guide on rare 50p coins and valuable money, here.
