Lindsay Preiss accidentally donated a mug with $6,500 in cash inside to Goodwill after attempting to tidy up her Atlanta home.

Her 27-year-old son sold his car and stashed the money in the mug to keep it hidden for a few days.

The family is now asking for the public's help to find the mug.

As the nation continues to be swept away in Marie Kondo's tidying-up tips, one mom in Atlanta is regretting following the lifestyle guru's advice.

When Lindsay Preiss donated her son's old souvenir mug to Goodwill, she thought she was getting rid of unnecessary clutter that did not "spark joy." It turns out that was a big mistake, because the mug was filled with $6,500 in cash.

Preiss's 27-year-old son, Devon Silvey, had just sold his car and stashed the money in the mug at his parents' house. In the process of tidying up, Preiss donated the mug to Goodwill — and now the family is asking for help to get it back.

"[I feel] like the worst mom in the world," Preiss told WSB-TV. "I mean, I feel terrible."

Silvey was in the process of moving apartments, so he needed a place to stash his money for a day. He thought an old Mickey Mouse mug was a perfect place. Since it was covered with a lid, Preiss couldn't see what was inside.

"At first I thought it was a joke or a prank or something like that," Silvey told WSB-TV. "She thought I was upset about the mug being gone, which, I miss the mug as well, but what was inside was a little more important."

After Preiss and Silvey contacted the Goodwill, store managers scoured hours of surveillance footage. They saw an employee price the mug and put it in a bin to be shelved in the store. From there, they can only assume that the mug was purchased.

Read more: Goodwill stores are filling up with cheap pieces no one wants — and it reveals a huge problem with the way people shop for clothes

The family is now offering a monetary reward to whoever purchased the mug and is willing to return the cash.

"We would be very, very thankful if you brought it back," Preiss told WSB-TV. "I'm just asking someone to please have it in your heart to do the right thing and give it back."

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