Michelle Martinez, 48, who owns more than 2,000 items of Mr Men memorabilia, said she “instantly fell in love” with the new coin featuring characters Mr Strong and Little Miss Giggles.
The commemorative £5 coin is the second in a series to be launched for this year’s anniversary and was designed by Adam Hargreaves, son of Mr Men creator Roger Hargreaves.
Marking the launch of the coin on Monday, Mrs Martinez said: “When I saw the coins were being released by the Royal Mint to celebrate the 50th anniversary, I instantly fell in love.
“Although I’ve been a collector of Mr Men for many years, these are my very first coins. I’m so excited to be adding them to my collection, and already can’t wait to get my hands on the next one.”
Mrs Martinez, who lives with her husband Stephen in Hampshire said memorabilia from the books had been bought by her family before she was born, and having taken up the interest herself ended up with more than 2,000 items in 2012 packaged into 45 crates.
But she added: “When it came out of the loft in January 2021 it was 95 crates. I have yet to recount the collection. That is the next mission.”
Mr Men first hit bookshelves in 1971 and has since gone on to sell more than 250 million books in 28 countries across the world, translated into 17 different languages.
A first coin celebrating the anniversary and featuring the character Mr Happy was released in February, with both now available to buy from the Royal Mint website.