UPPER DARBY, Pa. (CBS) – Police in Delaware County are trying to track down the origin of a five-pound brick of marijuana that was mistakenly delivered to an elderly couple last week.

Police say UPS delivered the package to a house in the first block of Heather Road, but the homeowners didn’t know the name on the package.

READ MORE: Timberwolves Spoil Embiid's 76ers Return With 2OT Victory

Upper Darby Police Superintendent Michael Chitwood says the couple finally decided to open the package, and that’s when they found the pot inside and called police.

Chitwood believes the stash — which he describes as “high quality” marijuana — is worth about $22,000. And he says this kind of thing is more common that you would think.

“During the course of a year, we’ll probably get anywhere from six to 10 of these types of things,” he told KYW Newsradio this morning. “Sometimes we can get a body associated with it and other times we can’t. More often than not, we see people waiting for the package outside and they say, ‘That’s for me.’”

READ MORE: 'It's Just Too Much.' Neighbors Remember 51-Year-Old Gunned Down In Poplar

Chitwood says the package had two Arizona return addresses on it; one in Tollison and one in Phoenix, but both were fake.

The federal Drug Enforcement Agency is expected to get involved in the investigation.

Reported by Brad Segall, KYW Newsradio 1060

MORE NEWS: Caught On Camera: Fire Rips Through Vacant Bar In Penns Grove, New Jersey