Singularity, issue 14 and the final Savage Starlight comic, sits on the driver's seat of a broken-down truck in the woods during the Jackson epilogue.
B. Pino's Firefly Pendant
B. Pino's Firefly pendant sits on a desk in the Hidden Pines Corral ranch house, in the Ranch House section of Tommy's Dam. It belonged to Brent Pino.
Foreign Element
Foreign Element, issue 5 of Savage Starlight, lies next to a body by a crashed car on the riverbed walk to the dam in Tommy's Dam.
Oliverio's Firefly Pendant
Oliverio's Firefly pendant is on the bottom shelf of a cabinet below the control room at the hydroelectric dam, in Tommy's Dam. It belonged to Ryan Oliverio.
Plant schematics
The Plant schematics are an optional artifact in the control room of Tommy's dam. You can only take them after the bandit attack: fight back through the control room and grab them from the central table where the two engineers stood earlier.