I've seen three tanks on their backs- not photos. One went off a railway flatcar while being unloaded after a movement, then had the poor taste to roll over after it then continued it's roly-poly ride off the loading ramp.
The second was a bridge job at Ft Knox, driven by a [You guessed it!] Second Lieutenant driver trainee getting his Armor branch introductory training. After he went through the side supports of the bridge he was on, he landed on the right side, in the water, and momentum did the rest. Happily, he pulled the escape hatch somewhere along the way and went out [up] after it was on its back, the driver and ground guide having abandoned ship before going through the bridge struts. It took four M88 VTR tank retrievers to pull that one out to where they could get to it.
The last one was an M48A3 in Vietnam. Not artillery, a command detonated 750-pound aircraft bomb. Blew the powerpack engine and transmission assembly out of the back and flipped the hull. Amazingly the crew all survived, not real badly damaged other than a driver with a broken leg and a few days total hearing loss by the turret crew, the turret retaining bars having snapped letting the turret separate from the hull.
What? WHAT?
M48A3 TANK EXPLODES A 750-POUND BOMB SET UP AS A MINE. Turret was hurled from tank, which was blown out of its tracks. *source*