After midnight, the Rebels were long gone and the Fifth Ohio Infantry, who were digging the guns (and claimed to be the only ones doing it), had already sent two down the hill, when:
“It was about this time that Corporal George W. Tyrrell, of Company H, Fifth Ohio, handed me the rebel flag that he had taken from the flag-staff of the redoubt. It was the usual bunting red flag, with the blue St. Andrew’s cross, with stars. I handed it in with my official report. Corporal Tyrrell afterward received a medal of honor for the capture of the flag referred to.”
This is as reported by Colonel Kilpatrick, in Sketches of War History, Volume IV, page 246-254 The Fifth Ohio Infantry at Resaca. The flag was forwarded to Washington by General Geary: from “Record of Rebel Flags Captured by Union Troops After April 19, 1861”, National Archives, RG 94.
This image is from a website that no longer can be contacted. The National Archive reports that all Confederate Flags were returned to their states under a resolution of Congress in 1905.