This way, my river lily!
This defunct Dairy Queen served as the location for the ‘flashback’ scenes. It was digitally or physically altered for the ‘present day’ shots. The forest shots are most likely filmed at this location too, as an interview with the 1st Asst Director indicated only 3 days of location shooting, two of which were in the Cartersville area, leaving only one day for this location.
MAP
(Guardians of the Galaxy Vol 2, 2017)
MCU: Location Scout 