"She creates one-of-a-kind matching tees for kids and adults, or at least she thought that they were one-of-a-kind creations," reports Oregon news station KATU.com.
Her most popular shirt is a black tank top with an American flag and the hashtag #merica on the front.
Recently, Lay was shocked when her friend spotted her shirt at a Target store in Seattle.
The retailer was selling the shirt for $12.99, twice what Lay charges.
She says she was "blown away" by the similarity between the shirts.
Lay has contacted Target about the issue, but isn't sure if there's anything she can do about it.
"I would have to spend thousands and thousands of dollars to fix this, and I still might lose," she told KATU. "I don't know what I'll do."
Target said it is aware of the shirt and is in the process of talking to the designer.