Ceramic shards, straight pins, and buttons are buried behind the museum around old trinities - three-story houses with one room on each floor, named after the Father, Son, and Holy Spirit.
Kelleher said trash from residents of those houses is treasure for archaeologists. When the team unearthed what might be a 150-year-old garbage pit during its second-to-last dig of the summer, it was like finding a pot of gold.
Analysis of nails helps date the artifacts. Fancy ceramics in humble immigrant housing is a sign of social mobility. Bones, leftover from meals, show residents' diets.
Volunteers, tanned from the sun and covered head to toe in dirt, shared their own stories while searching for artifacts.
Debbie Hadley's sixth-great-grandfather built two homes in the alley and a shop to sell imports such as molasses and rum. More than 200 years later, his descendant is uncovering bits of everyday life once lost in the ground.
"You find a little clay marble and imagine the kid that was playing with that marble," Hadley said. "It makes you wonder when you're walking around what else is buried beneath you."
Philippe Atallah, 15 and a rising sophomore at William Penn Charter School, wants to be an archaeologist. He quickly snatched up tiny needles and bits of shell as he scooped dirt into a bucket.
Gen Everett, who has an art deco trowel tattooed on her arm, is looking for an internship or job in archaeology. She welcomed the new experience after spending two summers digging for prehistoric artifacts in New Hampshire.
"It's really neat being part of this history," said Kelleher, whose Irish immigrant grandparents partly inspired her work. "You're sharing . . . and building your own rich history, and it's becoming interwoven with the history of the immigrants."
Contact Summer Ballentine at 215-854-2771 or at SBallentine@philly.com. Follow her on Twitter @esballentine.