According to Staten Island Advance, Matthew and Maria Colonna Emanuel had asked a local company to replace some trees in their backyard. It was the landscapers who discovered the safe, which they initially described as a "metal box."
"I thought it had something to do with electricity or something," Mr Emanuel told Staten Island Advance.
They pulled it out and that's when they noticed a dial, suggesting it was a safe.
After cracking open the safe with a pickaxe, the couple was stunned to find thousands of wet wads of dollars, simply rotting away. "And there are all these bags with hundreds and jewelry, diamonds, engagement rings, dozens of rings, gold with jade," Mr Emanuel told CBS New York. "It was stunning."
Why the burglar dumped the safe in their neighbour's home and never came back to retrieve the loot remains a mystery.
The Emanuels returned the cash and jewels to their rightful owners. "A couple of people asked us, 'Why did you return it?'," Ms Emanuel told CBS New York. "It wasn't even a question. It wasn't ours." Click for more trending news