Standard practice by Federal soldiers involved digging shallow trenches and moving Confederate dead into them ASAP. Due to the summer heat and the large number of Confederate dead left on the field, this would have been done as quickly as possible.

Even had they wished to do otherwise, Federal soldiers had no way to identify Confederate dead. Any temporary wooden markers have been gone for almost 150 years. I would be surprised if burial trench sites for Confederate dead in the Atlanta area are identified in any way.

Here's an image of Confederate dead collected for burial at Spotsylvania CH, VA., May 19, 1864. It's from Miller's Photographic History of the Civil War" and entitled, "Before the Sod Hid Them". Based on a few cursory mentions of battlefield burials in the Official Records, this scene was repeated countless times during the war.

Note the Federal soldiers in the burial detail in the upper right corner of the image. The last one in line appears to be holding a bunch of flowers in his right hand.