Davidson's Firefly pendant lies underwater in a stone rotunda in The Capitol Building section of The Outskirts. It belonged to Melinda Davidson and is easy to swim past.
Melinda Davidson won a place on a pendant through one of Naughty Dog's Firefly Pendant Contests.
Evacuation Leaflet
The Evacuation Leaflet is an old FEDRA warning on the right-hand pavement in downtown Boston. Once you climb the collapsed street and Tess and Ellie start talking about the bombing, look by the base of a traffic light a car has hit.
Field Ops Log
The Field Ops Log is a soldier's patrol record inside the Goldstone Building, the tilted skyscraper downtown. Climb the stairwell toward the fifth floor; it lies beside the second dead soldier, along with a couple of 9mm rounds.
Firefly Map
The Firefly Map is a note on a dead Firefly in the subway station downtown, on the stairs between the two escalators. It is the body to the right of the one carrying a Molotov cocktail.
Firefly Orders
Firefly Orders is a note on a dead Firefly at the bottom of the stairs you take after the cutscene in The Capitol Building section. Look to the right and behind you at the foot of the steps.