On her first day volunteering at a public library in Sterling Heights, Michigan, Helen Poniatowski was flipping through a donated book when something unusual caught her eye: a timeworn wedding photo tucked between the pages.

“I thought, ‘Oh, what a shame. Here’s this nice wedding photograph and we don’t know anything about it,’” said Poniatowski, 87, who, along with other volunteers, checks donated books for copyright details and forgotten items.