An American couple out walking their dog have struck it rich - unearthing a hoard of buried gold coins which experts have valued at more than $US10 million ($A11.12 million).
The so-called Saddle Ridge find is believed to be the most valuable treasure trove ever discovered in the US, according to Kagin's Inc, which specialises in ancient gold coins.
The couple, named only as John and Mary, spotted a partially-buried can jutting out of the ground - and after further digging found seven more, with more than 1400 gold coins.
"This family literally found the pot of gold at the end of the rainbow," said company boss Donald Kagin, adding that most of the coins date from the late 19th century.
"What's really significant about this find ... is that unlike other hoards and treasures, this one includes a great variety of dates, many of which are in pristine condition."
The Saddle Ridge Treasure is named after a feature on the couple's property in an area of northern California known for buried treasure since the Gold Rush in the 19th century.
The couple, aged around 40, said they were simply taking their dog for its daily walk when they made the first find.
"I saw an old can sticking out of the ground on a trail that we had walked almost every day for many, many years," said John, who used a stick to dig it out.
After further digging, including with a metal detector, they eventually unearthed eight cans.
