My old man was WWII Airborne, twice wounded (Ardennes and Germany). Though he never mentioned it, I wonder if the American troops knew of the 20 July attempt on Hitler...?
I believe that Supreme Headquarters in England was aware of it. Whether the news filtered down to the front lines is hard to tell. From what I have read I would say no, they were not. The only thing that concerned them was staying alive one more day.
Hitler broadcast on the radio that night, so it became worldwide news. After the successful D-Day invasion, everyone knew that Germany was doomed, it was only a matter of time. The plotters wanted to make peace with the Western Allies but continue to fight against Stalin. FDR and Churchill would never have agreed to that.