The man's foot was sticking out of the donation slot and he apparently injured his head in his efforts to reach inside the box.
The incident happened Monday morning in Lomita near Pacific Coast Highway and Cypress Street.
Firefighters were able to cut the box open and free the man.
He was treated at the scene for minor bumps and bruises.
The man was questioned and then released after he told deputies that he got stuck trying to grab his phone after it fell inside the box.