ChangeChecker's calculations suggest there are probably 935,000 Edinburgh City coins still in circulation.
On eBay, the highest price we've seen one of these coins go for recently was £11.59.
That means you could sell it for more than 10 times its face value.
2011 Wales Cardiff City £1
This coin was also part of the capital cities series, but it is slightly less rare, with an estimated circulation of 1,615,000.
Designed by Stuart Devlin, goldsmith and jeweller to the Queen, this coin depicts the circular Coat of Arms of Cardiff as the principal focus to represent Wales.
The highest price we could find on eBay recently for the coin was £11.01.
2010 London City £1
A third coin released as part of the capital cities of the UK series was the London £1.
The coin shows the portrait of the Queen and on the reverse side shows the four official badges of the capital cities of the UK, with a magnified image of the badge of London.
ChangeChecker estimates there are 2,635,000 coins left in circulation.
But you're unlikely to make a mint out of yours if you find one.
The highest amount we saw this £1 sell for was previously £2.99 on eBay.
2008 Royal Arms £1
There were 3,910,000 million of these £1 coins minted in 2008.
It features the Royal Shield of Arms coin, and shows various designs including lions and a heart on the shield.
If you think you’ve got a coin that could fetch a few bob then it’s worth getting it verified.
The Royal Mint can tell if your coin is legit and not counterfeit, but doesn’t do valuations.
In the meantime, if you want a coin valued you could contact Sovereign rarities - a team of coin specialists, collectively with over one hundred years of experience.
Stanley Gibbons, which specialises in stamp collections, also offers a free valuation service through its rare coin division, called Baldwin’s.
For more common coins you could try selling them online, via a website like eBay.