"I do believe that if you do something good, something good will come back to you," Goodwill employee Andrea Lessing said after finding the money

While thrift shops are a good place to discover forgotten treasures, one Goodwill employee stumbled across the find of a lifetime.

Andrea Lessing of Oklahoma recently found mounds of cash hidden away in a pair of sweaters that were donated to her store, according to NBC affiliate KFOR. Lessing was going through the articles of clothing as routine inspection before putting them up for sale.

"Just from working here a month and a half, I've realized that there are a lot of things that have been donated," she told the news station. "You want to make sure there's good product, there's no stains, there's no holes, there's no tears, there's no rips."

While Lessing initially thought the sweaters were holding books, she quickly discovered stacks of envelopes filled with $100 bills inside them.

In total, Lessing had stumbled upon $42,000 worth of cash, the outlet reported.

Fortunately, the envelopes also had paperwork that identified who owned the cash, and the store was able to return the money, according to KFOR.

"Normally we have no way of knowing who the money belongs to," Frank Holland, vice president of donated goods at the nonprofit chain, told KFOR. "Even if we wanted to try to give it back to someone, there was no way to find who that person was."

Lessing, a mother to a 6-year-old girl, admitted it was hard not to think of how she could have used the money if she could have kept it.

"I have a daughter, I love her very much and you can't put a price on my daughter," she said. "I know what could be risked stealing that money and I do believe in karma. I do believe that if you do something good, something good will come back to you."

RELATED VIDEO: Single Mom Whose Net Worth Reached $750K in 4 Years Shares Her Budgeting and Investing Advice

But Lessing wouldn't walk away empty-handed after all.

According to KFOR, the owner of the money surprised her with $1,000 from the money she found.

"Her birthday is coming up in July so I can actually give her an amazing birthday party," Lessing said of the reward.

But this recent Goodwill discovery isn't the only surprise to make headlines in recent years.

In 2018, a framed copy of a December 28, 1774, edition of the Pennsylvania Journal and Weekly Advertiser newspaper was donated to a New Jersey Goodwill store and estimated to be worth $18,000.

And in one unique instance, a customer bought a VCR that contained a VHS tape of a baby boy taking his first steps and was able to return it to the family using social media.