Jonathan Needham, 54, found the gold on the Staffordshire and Derbyshire border - and believes it was formed naturally beneath the ground there.
The nugget - shaped like England, Wales and Scotland - is almost 3cm in length and over 1cm wide and weighs 10.3 grams.
Retired tree surgeon and treasure seeker Jonathan says his ''Holy Grail'' find on November 1 is his ''most interesting ever''.
He is now in the process of confirming whether the piece of gold is natural or smelted.
The nugget as scrap could be worth around £800 - but if it is evidence of gold mining in the Midlands in the past it will be worth much more.
History buff Jonathan said: "I really could not believe it. I have dug gold before but I was not expecting to find a nugget of gold.
"When you are detecting in England to find a nugget of gold is exceptional.
"When I dug it I could see it was gold coloured and I knew straight away that it was gold - but I thought it could have been some bit of jewelry but it is not.
"It was quite funny - when I started cleaning it and turned it around I thought 'that looks just like England'.
"It is rare enough to find a piece of gold but to find one that looks exactly like England is crazy.
"The jury is out whether its natural or whether its part of a smelting process and the gold was smelted and then dropped.
"People are saying it's natural - if it is natural then I found this on the Derbyshire Staffordshire borders. It could open up a whole can of worms.'
"Some experts are going to have to look into it and if it is natural gold it is going to be worth a lot more money than scrap gold.
"I am hoping it is a natural nugget and if it is it would be extraordinary because not many get found in this country.
"If it is natural gold it will be one in a life time."
He is now hoping to return to the same area to see if he can discover more similar finds there.
He added: "I will be checking out the area very carefully to see if I can pull any more out - it is an amazing find."
Last year Jonathan discovered a "one in a billion" Bronze Age artefact - after founding the 3000-year-old dress or cloak fastener on a patch of land in Staffs.
Jonathan wanted to be a treasure hunter decades ago after watching TV about finds.
He is passionate about ancient history and loves watching The Detectorists.
But he was always too busy working - so had to wait until after arthritis forced him to go part-time to take up the hobby.
And now his hobby has turned into a profession.
"This is what I do. I am a treasure seeker I don't do anything else - this is my job," concluded Jonathan.
He now runs a YouTube channel where he shares his metal detecting adventures called The Detector-hist:
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