The wire from the breaker box is 2 plus ground, but the wire into the outlet box is 2 without ground, the boxes are plastic. The outlets are currently 2 prong. The house is from the late fifties. I would like to ground the outlets and install 3 prong outlets.

I don't get it. If the circuit has a ground at the panel where did the ground go at the receptacle?

That is confusing to me also. I can see the ground wire at the panel the white and black are entering the outlet boxes

If you have wiring from the fifties and plastic boxes, someone has replace the metal boxes with plastic and didn't know what to do with the ground wire. Probably clipped it off at the end of the sheathing. I'd try to pull the cable further into the box and see if you can splice on 6" ground wire.