Do you have a hugely valuable coin just sitting in your pockets? It's worth checking your change, because there are a number of coins that few people know about - which could be worth a small fortune.
Some coins have gained fame for their collectability. So, for example, the Kew Gardens 50p - featuring the famous pagoda on the reverse and celebrating 250 years of the gardens, is well-known for being worth anything up to £50.
The problem when coins get famous is that people hunt them out in their change so there are more sellers. Meanwhile, collectors tend to have them already, so the price goes down. Nowadays, most eBay sellers won't get anything like £50 for their Kew Gardens coin.
The key is therefore to track down less well known collectible coins - or ones that are rare enough to hold their value anyway.
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1. The Blue Peter Olympics 50p
This was designed by a viewer in 2009, and sold in collectors' packs for £1.99. Fewer than 100,000 of them were minted, which makes it at least twice as rare as the Kew 50p. The Daily Mail claims, in fact, that fewer than 20,000 were sold.
Before you start looking for the coin and getting your hopes up, it's worth highlighting that in 2012, the same coin was struck again in far higher numbers. It means that if you find the coin, you then need to check the date on it, because only the 2009 coins are considered collectible.
2. The Peter Rabbit 50p
These were only released at some attractions and National Trust properties, and the Royal Mint has never said how many are in circulation. It means they are considered collectible and can fetch up to £15.
3. WWF 50p
This 2011 coin sells for up to £10.
4. The Royal Arms coin from 2008
It's a very common design, but according to The Mirror, in 2008 so few were produced that it make this the fourth rarest pound coin - and therefore worth about £6.
5. The 2011 Edinburgh design
It was the only £1 coin of which fewer than 1 million were made. It sells for up to £5.
6. The Charles Dickens £2 coin
This coin was famously released in relatively small numbers in 2012 and is worth up to £4.
7. The 2002 Northern Irish Commonwealth Games £2.
There were fewer than 500,000 minted, so they sell for up to £25.
If you really want to make money from your change, then you need to look out for those featuring mistakes. Many of them are relatively well-known, but they are so rare that this hasn't flooded the market, and they are still worth a fortune.
8. The 2012 Olympics aquatics 50p
One of the most valuable is a coin from the 2012 Olympics - famous for being worth up to £1,000. The coin in question was celebrating the aquatics team, and features a swimmer. In around 600 early versions of the coin, the water is seen over the swimmer's face, but the designer wasn't happy, so they changed the design so there are no waves on the face. It's the early ones with the obscured face that are worth the money.
9. The dateless 20p from 2008
These were printed with no date on by accident - when the mint was switching the side the date appeared on. Around 250,000 were printed with the error and they are worth around £100.
10. The 1983 New Pence 2ps
Before 1982, all 2ps had the words 'new pence' on them: from 1982 they feature the words 'two pence' instead. By mistake in 1983 a number of 2p were printed as 'New Pence', which are worth more than £100.
And it's not just coins you should watch for. There has been plenty of chatter about the new £5 notes, and what they might fetch if you have one with a very low serial number on it. However, the ones you really need to keep an eye out for are the four which have been engraved by artist Graham Short, with a tiny portrait of Jane Austen on them.
One has been released into circulation in England, one in Northern Ireland, one in Scotland, and one in Wales: Short revealed that he paid for his lunch using one at a cafe in Blackwood Wales. If you find it, it could be worth £50,000.