The agency said Thursday evening in an email it is following up with a producer of the product, but it provided no details on the company involved.
Tammy Jarbeau, a spokeswoman at the federal agency, said its officials are looking into the possibility of food tampering.
The RCMP said earlier in the day it is investigating the three cases.
Police say a resident contacted them on May 19 after finding a nail in a potato from a bag of Farmer's Market spuds. The bag was purchased from the Atlantic Superstore in Antigonish in late April or early May.
A nail in another Farmer's Market potato purchased at a No Frills grocery store in Barrington Passage was reported to RCMP on May 20.
Prince Edward Island RCMP also say a customer turned in a potato with a metal object in it on May 18.
Investigators say it was purchased from the Atlantic Superstore in Montague.
No injuries were reported in any of the cases.
The agency says as a precaution, consumers should carefully check potatoes for foreign objects.