Fort Pierce police said a clerk found the 3-year-old crying and asking for his "mommy" at Deal's Dollar Tree Tuesday evening and the child was unable to remember his mother's last name and calls over the public address system failed to get a response, TCPalm.com reported Friday.
Investigators said the mother returned at 9:44 p.m., about an hour after the child was found, with the boy's grandmother.
"She said she thought he was in the vehicle at the time she left the store," the police report said of the mother. "But couldn't find him when they got home."
The mother, who police said seemed confused, was unable to offer any explanation for why it took her an hour to return to the store.
Philleana Peak, 30, was arrested on charges of child neglect and possession of marijuana. She was taken to the St. Lucie County Jail with bail set at $6,250.
Police said the child was released into the custody of his grandmother and the Florida Department of Children and Families has been notified.