Buried treasure is a very real thing. And from time to time, people find it without even trying. Sometimes, it’s mere happenstance. Other times, it’s amateur treasure hunters with metal detectors who hit the mother lode.

Curious about some of the treasures that have been discovered underground? Here are some of the most valuable things ever unearthed.

A massive gold nugget in Mexico

Close up on gold nuggets
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In 1989, a treasure hunter was exploring the desert surface of Sonora, Mexico with a metal detector he’d bought at a nearby Radio Shack. After finding plenty of nails and junk, he started to get a clear signal that he’d hit something.

It was gold ... and lots of it. He’d discovered a massive gold nugget weighing about 389 troy ounces (a unit of measurement used for precious metals). Not impressed yet? You might be when you learn that 389 troy ounces is about 26 pounds. That’s an awfully big nugget ... and it makes this one the biggest known placer nugget in the Western Hemisphere.

Given its unique, shoe-like shape, the nugget was dubbed the “Boot of Cortez.” The Boot made the rounds in museums and mineral shows but was eventually sold in 2008.

$10 million in coins in California

Gold bars and coins
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Imagine walking your dog... and coming across buried treasure. This isn't the plot of a fun movie: It's a true story for a California couple who had their own unexpected gold rush when they discovered a multi-million dollar treasure on their property.

On seeing a canister peeking out from below ground, they got curious and unearthed it, only to find a bounty of gold coins. Upon further inspection, there were actually several cans full of coins: over 1,400 in total.

They joined forces with coin experts to clean up the findings and assess what they’d found. It was determined that the coins were estimated to be worth a whopping $10 million. Not a bad reward for walking the dog!

Star rubies in North Carolina

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While fishing outside of Asheville, North Carolina, a rock enthusiast noticed traces of corundum in a stream bed — a sure sign that there could be gems nearby.

He followed the trail in the stream bed, and it turned out that he was right. After digging eight feet down over a period of years, he found an incredible treasure: a series of star rubies, a particular type of ruby with radiating lines that look like little stars in the center, which are a whole lot less common than regular rubies.

Sadly, the man who discovered these rubies died before they could be sold. Had he lived to see the sale, he probably would have been pleased by their haul: They are worth an estimated $90 million!

A Roman treasure chest in England

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After losing his beloved hammer, a farmer in Suffolk, England, asked a friend and metal detector hobbyist to help him find it on the grounds where he worked. While looking, they found something much better than a hammer: jewelry, gold and silver coins, and cutlery.

An excavation went underway, and the resulting treasure consisted of nearly 15,000 objects. Oh, and in case you were worried: the hammer was found, too.

These days, the treasure now lives at the British Museum in London, where many of the pieces are on permanent display. The value? An estimated 3 million pounds, or close to $4 million USD.

Down on the ground!

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Sometimes, treasure can present itself in the most unlikely places. So be sure to keep your eyes on the prize... or, rather, the ground! After all, who knows what treasures could be lurking under your feet?