After you complete the first chapter you will be exploring Jeet's Territory. At the southern edge of the Fuel Veins region there is a Scavenging Location in the hold of a ruined half boat. Inside the boat next to the only pile of scrap is a rotting corpse filled with maggots, simply hold A next to it to trigger the eating of maggots and an easy 3 GS is yours! Attached are pictures of the location on the map and it on foot.