According to court papers, Sean Mace is claiming that employee negligence led to his injuries.
Mace, who used to be in the US navy, says he was under a false Monkey Puzzle tree in San Francisco Maritime National Historic Park in October last year when the pine cone dropped on his head.
He says he’s had to have two operations for a “traumatic brain injury”.
Court papers also say he’s been left with “severe and likely irreversible cognitive defects” after the surgery to relieve swelling caused by internal bleeding on his brain.
Sean Mace is claiming financial damages of $5m (£3.2m) for personal injury and losses caused by “the negligent or wrongful act of omission of any employee”.
He’s named the park, the US government, the National Park Service and the Department of Interior as defendants in the case.
His lawyer Scott Johnson says he needs a third operation.