From wherever you are, fast travel to the Becker Farm. A close, free fast travel point is The Crater. Once you arrive at the farm, be prepared to run into a couple of Feral Ghouls — double win if you have an active ghoul challenge. The path is pretty straightforward — for the Toxic Valley, that is. Just jog or run west toward the corner of the partially standing clapboard house on the right. From the corner of the home, bear right as you head toward the poisoned creek and a small fragment of a standing, red clapboard wall. Just before you get to that wall, you'll see the telltale gravelled mound of earth hiding the treasure. Oh, and don't forget to check for a bobblehead or magazine in the house.
Toxic Valley Map 01 — The Becker Farm Hoard and Loot