Normal house and job-site debris is fine. The limits come from California law and from what the county transfer station will take off the truck.
California treats every mercury-containing device as hazardous waste once you throw it out, and the county is blunt about the consequence: it is illegal for anyone to put hazardous waste in the trash. That covers old thermostats, mercury thermometers, gauges, and mercury switches.
Electronics are banned from the trash statewide for the same reason. The county's list is long: televisions, computers, monitors, printers, fax machines, stereos, DVD players, phones, answering machines, electrical cords, and even holiday lights. Keep all of it out of the container.
The transfer station has its own refusals worth knowing before you load. It won't take large loads of concrete, soil, rock, gravel, or asphalt, logs or tree stumps, pressure-treated or creosote-coated wood, liquid waste, or drums bigger than five gallons. Small loads of clean rubble are fine.
Got something that doesn't fit any of those boxes? Ask your account manager before it goes in the container.