Authorities said a farm worker made the gruesome discovery at about 9:30 a.m. in the 3200 block of Central Avenue in Nyeland Acres, an unincorporated part of Camarillo.
Investigators are trying to determine who left the baby in the field and why. No one has been arrested.
The man who found the body, Gabriel Ortiz, says a placenta was also found nearby, so he believes the baby was born at the strawberry field.
Investigators believe the baby was carried full term.
"We're also concerned about the health and physical well-being of the mother," said Sgt. Eric Buschow of the Ventura County Sheriff's Department.
Authorities say they need the public's help finding the mother of the baby. Anyone with information is urged to call the Ventura County Sheriff's Department at (805) 384-4721.