Their rarity means they are worth a great deal to collectors.
In May, a 2015 dated silver 2p coin was dropped into a Royal British Legion collection tin in Wiltshire and later sold at an auction for nearly £1,400.
e Bay was founded by Pierre Omidyar in 1995, and became a notable success story of the dot-com bubble.
While this might sound like a lot, usually when a new 50p is printed more than five million are struck.
And with a total of 950 million 50p coins currently in circulation, the Kew Pagoda coins can be incredibly hard to spot.
If you get your hands on one, numismatists — or currency collectors — are typically willing to pay around £30-50 on online marketplace e Bay.
In 2008, the Royal Mint launched a Royal Shield of Arms series of coins.
An entrepreneur who got bored of working as a labourer on a building site now makes up to £70,000 a year selling rare coins on e Bay.