The family had been cleaning out the home, which had decades-worth of belongings stored in it, for a year before they made the discovery, Reyes told

After struggling to find a bank willing to exchange them for cash, he was urged by one manager to look into whether he had a stash of rare pennies worth more than their dollar value.

Reyes has now listed the coins on OfferUp, a popular resale app and website, asking for $25,000 – more than double the $10,000 value in normal currency. ‘Someone can buy them and they can go penny hunting,’ he said.

Reyes has now listed the coins on OfferUp, a popular resale app and website, asking for $25,000

Realtor John Reyes made the discovery when cleaning out his late father-in-law’s former home in Los Angeles, California

Rare coins can make a mint. Last month a coin expert revealed the most valuable pieces he has ever sold at auction include a $12million silver dollar and a set of Lincoln pennies which fetched $7.7 million.

Reyes has had piecemeal offers, but is waiting for someone to take them completely off his hands.

Fritz and his brother, who were both German immigrants, lived in the home for decades until he pᴀssed and his brother moved away.

Reyes told DailyMail.com how he is sure Fritz had kept the coins because of their copper value.

In the 1980s, the US Mint anticipated an increase in the price of copper, and so switched to making coins out of zinc in a money-saving move.

‘The moment that my father-in-law knew that they were switching over to zinc, then he would have started collecting. That’s just the kind of man he was,’ said Reyes.

‘He never told us they were there but he always said that whenever his time came that we should make sure to go through the house and take our time with it. So he at least gave some hints on some things!’

Reyes said that the family had left the basement until last when cleaning out the home as everyone was tentative to go down there and it was ‘full of spiderwebs.’

The house was on a raised foundation, he said, with a crawlspace beneath which was filled with heavy items.

It was when he was pulling out a heavy carpet from inside the crawlspace that he made the discovery.

In the 1980s, the US Mint anticipated an increase in the price of copper, and so switched to making coins out of zinc

Reyes said he is sure his father-in-law had kept the coins because of their copper value

‘That’s when I saw some rolls of pennies,’ he said. ‘And as I started to move more stuff out, that’s when I found boxes of pennies, and then crates of pennies.’

These crates were so heavy that it took them half a day just to move them to the ground, but beneath they also found old bank bags also filled with coins.

Some of the bags were even lead-sealed by the banks – a handful of which do not even exist anymore.

‘I’ve been told by coin experts not to open the bags as they themselves are valuable,’ he told DailyMail.com.

After making the discovery, the family thought they would just cash out and be done with it.

‘When I called banks in LA nobody wanted to take them. I thought it would be easy and I would just take a few wheelbarrows in at a time,’ Reyes said.

One Wells Fargo branch said they could not accommodate them as it would not fit in the vault.

Their local bank in Ontario, California, did not want to take the pennies either, and urged Reyes and his extended family to go through them and search for any rarities.

‘The value is in the uniqueness,’ Reyes told KTLA, adding that taking less than their full value would go against the ideals of his father-in-law.