The first Toyota model built at the NUMMI plant in California was the Corolla, specifically the Corolla FX16. Toyota and General Motors created NUMMI in Fremont in 1984, and the plant began producing Toyota vehicles in September 1986.
The wording can cause a historical mix-up: the first vehicle produced at NUMMI was a Chevrolet Nova, which was mechanically related to the Toyota Corolla and sold by GM. The first Toyota-badged vehicle from the plant, however, was a Corolla FX16. That makes Corolla the correct Toyota model answer.
NUMMI later built several Corolla generations, as well as Toyota compact pickups and Tacoma trucks. The joint venture became an important test of Toyota’s production system in the United States. NUMMI closed in 2010, and the Fremont facility was later acquired by Tesla.