GLEN CARBON, Ill.—This stacks up among the better finds at a Goodwill store: $7,500 in cash stuffed in a shoebox.

A recent Bulgarian immigrant found the money during her first day on the job last week at a Goodwill near St. Louis in Glen Carbon.

Teodora Petrova didn’t hesitate after finding the cash with a pair of donated shoes—she turned the money over to a manager who told executives for the nonprofit charity.

The president and chief executive of the area’s Goodwill organization says it’s eager to find the owner of the money. The charity figures it may have been left with the shoes accidentally.

If the owner isn’t found, Goodwill says the money will go toward the charity’s job-placement efforts.