PORTLAND -- A Wilson High School student thought she was taking part in a harmless senior prank, but learned it may cost her a diploma.

KGW photo

The lawn where seniors made the peace sign.

In the dark of the night, dozens of Wilson High School students dug up some of the sod in the school’s courtyard and in its place, planted flowers in the shape of a giant peace sign.

Tuesday morning, Maggie Collins admitted to Newschannel 8, that she was part of the prank.

She explained, “We wanted to do something that wasn’t destructive.”

But Wednesday afternoon she found herself in the principal’s office.

She says the principal told her she could not be able to graduate until she covered the cost to move the flowers and fix the lawn.

“Right now they're withholding my diploma until I get it fixed, and graduation is June 1 so I have to get this fixed by June 1,” said Maggie.

The school says when they dug up the sod, the students caused thousands of dollars in damage.

And since Maggie has been the only student to come forward, she has to pay for it.

Maggie says she doesn’t have that kind of money.

Maggie's mother, Alyson Breathed, says she was told her daughter would not be able to graduate if she didn't pay or name the other kids involved.

“They were encouraging me to encourage her to out the other kids and I don't encourage her to do that,” said Alyson.

Wilson principal Sue Brent told us off-camera that Maggie would still be able to graduate and even go through ceremonies, she just would not get her actual diploma.

Brent says this fine is just like any other school fine.

If you don't pay, you don’t get your diploma.

Maggie says she's now scrambling to come up with the money.