The accident was reported around 7:50 a.m. near Railroad Avenue in Vallejo
The California Highway Patrol said one of the big-rig drivers suffered major injuries and was taken to John Muir Medical Center in Walnut Creek.
CHP officer Peter Van Eckhardt said the big-rig that spilled the load of corn grain was a 1995 Peterbilt with two dump trailers.
The other big-rig was able to drive from the accident scene, Van Eckhardt said.
The lanes were cleared by 10:40 a.m.