By Cristy Gimbel

Toledo, OH (WTOL/CNN) - A little girl thought she'd hit the jackpot when she found a $20 bill. Turns out, the treasure was a fake.

The child's mother said it all started with a game. The kids were challenged to pick up the yard, and the child with the most trash would win a $5 prize.

"My daughter had the most garbage. Well, I find out she had cheated. She went over to the other yard on the other side of this gate over here as you see and found some garbage over there," said Jeweline Cole.

That's where the 8-year-old found something special.

"She just up and said, 'I found $20!' And oh my," said Cole.

She says her daughter was so proud of her new found cash she volunteered to pay for her school field trip herself with the money.

The girl attends Clay Avenue Community School. It was her principal there who first noticed something was up with the $20.

"It was quite evident when we looked at it. It was not the normal size of the currency," said Principal Julie McLaughlin.

McLaughlin says a similar incident actually happened two years ago with another child, so they took the bill away.

"We contacted police immediately and it's under police investigation," said McLaughlin.

Cole's daughter returned home without the money or any change. Cole called the school to find out what had happened.

"They told me it was counterfeit. And I was like, 'What? Counterfeit," said Cole.

Toledo police say they won't be charging the girl or her mother, but Cole says she is worried about where the money came from.

"A $20 bill just there out in the open like that. Where could it have come from? You know? Is there something going on in the neighborhood I don't know about," said Cole.

Toledo police have sent the case to the Secret Service for further investigation.

WTOL/CNN