When you next get a 50p in your change, don't be in a hurry to spend it or stick it in the car parking machine. Instead make sure you check your 50 pences because there are some out there that are worth tons more than their face value.

There are currently 54 different 50p coins in circulation. The rarest 50p of all is the Kew Gardens design and it's worth up to £185 on auction websites (in mint condition of course).

And the Kew coin is not the only one collectors are willing to pay a lot more for.

Right now there are seven 50p editions in circulation that are classed as 'scarce' and 47 more that are classed as potentially valuable.

According to the coin experts at ChangeChecker, the rarer the coin the more valuable it is.

Its website has created a scarcity index which tracks the 54 circulating 50p coins based on their worth. Check it out if you've a jar full of silvers stashed away somewhere.

Which 50p coins are valuable?

Expert Philip Mussell, the director of Coin News, on what coins belong in the piggy bank and which belong on eBay had this to say.

He told the Daily Mirror: "There are a few different ways this happens.

"One is when a mistake is made by the Royal Mint, like a 20p without a date, for example, or a 1983 2p coin accidentally printed with the old wording 'New Pence'. Mistakes are eminently collectable.

"Other collectibles are redesigns or limited edition releases. For example, an Olympic 50p with a swimmer was recently re-released.

"The first minting had a swimmer with waves obscuring her face but the designer didn't want that, so they unobscured her face and made it clear of wavy lines. That's now quite collectable."

Kew Gardens 50p

The Kew Gardens 50 piece was released to celebrate the 250th anniversary of the foundation of Kew Gardens.

The Kew Gardens 50p tops CoinChecker's scarcity index list.

It's stamped with the Kew Gardens Pagoda and with just 210,000 minted compared to a standard minting of around five million, it's classed as very rare.

That means they can sell for anything above £30 if you can find a collector. On eBay, they are selling for as much as £185.

2012 Olympics 50 pences

The London 2012 Sports Collection comprises 29 50p coins representing the 29 Olympic sports. There are 29 Olympic coins, but the football edition is classed as the rarest (although still over one million were struck), write the Birmingham Mail.

Designed by journalist Neil Wolfson, the coin was created to encapsulate football in a simple image. As the offside rule is a perennial talking point, the image is designed to provoke discussion, which was what Wolfson was aiming for.

"The Olympic Sports 50p series was a revelation in coin collecting – for many it represents the start of their interest in UK circulation coins and thousands rose to the challenge of finding them all from their change," explained ChangeChecker.

Beatrix Potter 50p

The Beatrix Potter 50p coins caused quite a stir when they were announced by the Royal Mint in 2016.

In March last year, a batch of Peter Rabbit coins entered circulation in the Lake District and a few other British locations related to the works of Beatrix Potter.

Shortly after, they started appearing on online marketplace eBay for far more than 50p shortly afterwards.

There are three different sets of five Beatrix Potter 50p coins - Peter Rabbit, Jemima Puddle-Duck, Mrs Tiggy-Winkle, Squirrel Nutkin and a special 150th anniversary coin.

The 2016 Beatrix Potter 50p coins rank highly in the scarcity list, with Jemima Puddle-Duck and Squirrel Nutkin coming in at numbers 6 and 7 – based largely on the fact that not many people own them and they are in very high demand.

If you've not been lucky enough to get one this time around, the Royal Mint has just released a new batch of Beatrix Potter coins - with some in colour - but they'll cost you £60.

WWF 50p

This special edition features 50 tiny animals with the WWF panda at its heart. This special edition features 50 tiny animals with the WWF panda at its heart. This commemorative coin is selling for more than £10, even if it has been in circulation a while and is no longer in mint condition

Euro 50p

This 1992 50p piece featuring 12 stars and representing the EC Single Market has been known to sell for around £50-£55 online.

These are the old-fashioned chunky 50 pences so you are unlikely to turn one up in your change, but it could be worth checking any long-term penny jars for.

But be aware

Be careful when buying as some of these standard coins are being advertised at massively inflated prices. However, a few of the rarer editions are selling for hundreds of pounds – so look carefully when comparing.