Vigil's Firefly pendant is the first Firefly pendant in The Quarantine Zone, lying on the floor of a bedroom in the Beyond the Wall section. It belonged to David Michael Vigil, and you only get one chance at it.
David Michael Vigil is a real fan who made custom Naughty Dog memorabilia and won one of the studio's 2013 fan art contests, which put his name on this pendant.
Boston Q.Z. Map
The Boston Q.Z. Map is the first artifact in the game and you cannot miss it: it is already inside Joel's backpack when you pick the bag up off a table in the smuggling tunnel during Beyond the Wall.
Docks Note
The Docks Note is a gripe from one of Robert's smugglers, lying in the big warehouse at Mission Hill Pier where a fishing boat hangs over the loading bay. Look on the right side, against the railing behind a blue trash bin.
Drafting Notice
The Drafting Notice is a FEDRA work order lying in a heap of papers in the Boston slums. After the bus where Malick confronts Joel, walk straight on between a vendor's stall on the left and a canopy on the right; the notice is on the ground at the corner.
Glueck's Firefly Pendant
Glueck's Firefly pendant hangs from a tree branch in the Beyond the Wall section of The Quarantine Zone, so you have to knock it down. It belonged to Ben Glueck.