I took toilet off and turned water off, then got 100ft snake down the drain it went all the way but when we pulled it out we had clay and dirt. We still have the water backing up through only the downstairs toilet. When it first started everyone was asleep so no one even flushed the toilet. It just started overflowing, it flooded,needless to say it really stunk downstairs. We called the city and they say the lines on the street are clear any ideas?

This job is over the heads of most DIYers. Call a plumber with a 200' snake and a camera. You need to reach the street riser so meausre how many feet from the back of your home to the far side of the street, frequently more than 100'. A plumber can run his camera and determine what you have and how far out, that's where he will dig. Think you have a collapsed pipe which needs to be dug up

Since the toilet is the lowest part of the drain system, it will flow out there. Water can't rise above the toilet unless the toilet itself was totally blocked. If you are getting dirt in a sanitary system that is connected to a county sewer, you have a break in the pipe somewhere. You might need to use a camera to find the exact spot.