Check your pockets. Have a little look down the back of the sofa. And empty out your piggy bank.

Because you may have a small fortune hidden away which you didn't even know about.

It has come to light that a variety of regular-looking coins that have been in circulation for years could be worth much more than their face value.

Some rare and special edition 50p, 20p, 2p and £2 coins have sold for far in excess of their normal value.

Here is what we know so far – check your shrapnel to see if you have any of these common coins with high price tags.

Kew Gardens 50p piece - £50

The Kew Gardens 50p was released in 2009 to celebrate the 250th Anniversary of the Royal Botanic Gardens
The Kew Gardens 50p was released in 2009 to celebrate the 250th Anniversary of the Royal Botanic Gardens

A special edition 50p piece with Kew Gardens on the back is currently changing hands for more than £50.

Collectors have been clamouring for this rare piece of coinage, produced in 2011 to mark the 250 anniversary of the Royal Botanical Gardens.

Only 210,000 coins were produced by The Royal Mint, compared with the 22.7 million featuring the Royal Arms in 2008 and 7.5million with a Girl Guiding design in 2010.

Dateless 20p piece - £100

The dateless 20p piece can be worth hundreds of times its face value
The dateless 20p piece can be worth hundreds of times its face value

A production error on the part of The Royal Mint made an inadvertent hero out of whoever was behind a 2008 run of 20p coins.

The Mint decided to switch the date from the reverse of the coin, to the front, however a production error meant the new and old designs were mismatched – leaving a date on neither side.

Somewhere between 50,000 and 200,000 coins were put into circulation before the mistake was spotted, and a mint-condition coin now sells for up to £100.

London Olympic 50p coin - £3,000

The London Olympics aquatic 50p
The London Olympics aquatic 50p

A lasting legacy of the London Olympic games was a series of 50p coins with one of 29 designs on the back.

Some of the designs were produced in higher numbers than the rest, and a full set would normally go for £35.

Some of the rarer designs featuring football, wheelchair rugby, wrestling and tennis, can be exchanged for £3 or £4 individually.

However, the most sought after, listed for £3,000 on eBay, is one of 600 original aquatic coins, showing water passing over a swimmer's face, before the design was altered to show a visible face of the athlete.

The EC commemorative 50p coin - £20

The Council of Europe 50p
The Council of Europe 50p

One for Remainers perhaps. In 1992 and 1993 the Mint issued a commemorative coin to celebrate the British presidency of the council of Europe. Just 109,000 coins were issued, compared to the usual 5 million to 12 million, making it highly collectable.

The coins are no longer in circulation because the 50p piece was reduced in size in 1997, but if you have one in your penny jar at home it could be worth as much as £20.

The 1983 'New Pence' 2p coin - £650

The 'new pence' 2p
The 'new pence' 2p

After British currency went decimal in 1971, all 2p coins had New Pence on the reverse until 1981.

The Royal Mint decided to replace New Pence with Two Pence in 1982. However, in 1983 the Mint accidentally produced a small number that bore the old inscription New Pence. These went into special collectors' sets, but if you do find one that made its way into circulation it could be worth up to £650.

Guy Fawkes £2 coin - £16

Some Guy Fawkes £2 coins included a misprint
Some Guy Fawkes £2 coins included a misprint

The Royal Mint regularly releases £2 coins with different designs and inscriptions on the edging. This means, however, that mistakes sometimes creep in.

The Guy Fawkes coin was released in 2005 to commemorate the 400th anniversary of The Gunpowder Plot to blow up the Houses of Parliament.

On some of the coins released into circulation the inscription read "Pemember, Pemember the Fifth of November instead of "Remember, Remember".

Those coins usually sell for around £16 on eBay.

Charles Dickens £2 coin - £8

The Charles Dickens £2 coin
The Charles Dickens £2 coin

In 2012 the Mint released a £2 coin to commemorate the 200th anniversary of the birth of Charles Dickens.

The detailed reverse profile feature the names of the author's books. Only 20,000 coins were minted, making it a collectible coin worth up to four times its face value.

Mary Rose and King James Bible £2 coins - £6

The Mary Rose £2 coin commemorating the 500th anniversary of the launch of the famous ship
The Mary Rose £2 coin commemorating the 500th anniversary of the launch of the famous ship

This rare coin marks the 500th anniversary of the Mary Rose - Henry VIII's mighty warship, which sunk in the Solent in 1545.

Both designs were released by the Royal Mint in 2011 in limited editions of 20,000 each to mark the 500th anniversary of the Mary Rose and the 400th anniversary of the King James Bible.

Both coins are already becoming collectible due to the small numbers and reach double to triple their face value.