Linzi Marriot posted on Facebook that she had been lucky enough to stumble across the Kew Gardens 50p coin in her change yesterday.
She posted: "Omg!!! I’ve been collecting coins since I was a little girl so to get this bad boy in my change today, I’m just so happy!! #rare50p #kewgardens"
Andrew Stuart Davidson replied: "I've never see one I collect 50p this is worth the most in good condition."
Lakeside Doncaster: Major search launched by emergency services after man gets into difficulty in water
Sheffield weather: Met Office issues thunderstorm warning as heatwave set to end with heavy rain and lightning
Popple Street Sheffield: 'Several' people arrested as street is cordoned off by police
South Yorkshire heatwave: 'Avoid the area' warning as five crews tackle large wildfire
Rivelin Valley Road Sheffield: Body found after police search of Rivelin Valley
The Kew Garden 50p coin was created to celebrate the 250th anniversary of London's Kew Gardens and only 210,000 of these were released.
This is compared to other 50p coins, including the 2008 Royal Arms coin, which was manufactured 22.7 million times.
It is believed to be worth around £50 but some have been listed on eBay previously for up to £300.
Other rare 50p coins usually only sell for around 10 to 12 times face value when they are sold on.
The Royal Mail has declared the Kew Gardens coin the rarest in circulation and changechecker has it listed as number one on its list of 54 rare coins.
The next four scarcest coins are all from the 2012 Olympics; Football, Triathlon, Judo and Wrestling.
Recently, the Royal Mint issued Beatrix Potter 50p coins which rank highly with Jemima Puddle-Duck and Squirrel Nutkin coming in at numbers six and seven.