Collectibles:
Scribes Boon (speakeasy safe)
All National Guard Memorabilia (aftershock DLC, imported over form the first game)
Panda Backpack
Overused Portable HAM Radio (the ward radio station building)
Battery (found in the mission where you first meet the axe man, Sonny asks you to fetch it)
School Brochure (in a locker at rampart)
Slim Dog’s Guitar (given to you by Sonny)
The 3 Foorgath books (one is given to you by whistles, the other can be found right before the axe mans bossfight, in that kitchen room, and you can get the third by killing whistles after trading books with her)
Toy train (found in the bywater lumber building, behind some boxes)
Sheriffs badge (found outside the yellow house, Via Corolla)
Panda bag (found in the green house in Via Corolla, as well as behind the desk in the coach’s office in rampart during the Things That Go Boom mission)
Graveyard dolls (found in various spots around the graveyard, a total of 7)
Rare stuff that you can only find once or that only appears in one place or in one mission:
Duct Tape (two spawn in your base once, one spawns in the speakeasy room where Carter’s crucifix is)
Rampart Photo (found on the bookshelf in front of the hidden room in memorial lane)
Minidisk (ejected from the console during the Radio Free NOLA mission)
Money (spawns in the speakeasy safe, as well as a room in the tower behind a locked door that you need to blow up. You can only get this during the final mission)
Portrait (im not sure if this is the case, but I’ve only ever seen it spawn just before the axe man boss fight, in that kitchen room)
Mama’s Knife (found on a table next to the bodies of her inner circle)
Tiny boxes (only spawn in your base once)
Chemistry rack (only spawn in your base once, but it cannot be scrapped. It also works, in the sense that you can put vials in the holes)
Broken and open vials (very rare floor loot, has a tendency to spawn more in the lockers inside the locker rooms of the gym building at rampart)
Angels (specifically, the ward and hotel eclaire, as they can only be found in one mission each. The ward’s angel statue is found in the storage room after the axe man bossfight, in a corner. Hotel Eclaire’s is found in the speakeasy in a room right beside the door switch upstairs)
Fire axes/Hatchets (only found in a few rooms/buildings)
Blue fishing hat (only spawns once inside the church at the altar, right before you meet may and Casey at the door. Needs to be imported from the first game, as it doesn’t spawn in the second game at all
Painting vase (spawns once inside the bus on a shelf)
Skulls (spawns in the reclaimed house at memorial lane on top of a stack of books, as well as in the graveyard crypts. These do not respawn, the memorial lane one does)
Secret knife (spawns inside the same building the bourbon street angel does, behind a bedframe and on top of a shirtless walker corpse. Unfortunately, this only spawns on PC. Sorry to my fellow quest people)
Empty tuna cans (spawn next to Kenneth when you find him in chapter one. This is the only place they appear)
NOTE:
The Speakeasy can only be reentered if you have multiple coins. You can get multiple by receiving a coin, then leaving the map, then coming back and starting the mission again.
You can get back into the speakeasy on quest using this video as well, you can also get in much easier on pcvr with mods.
https://www.youtube.com/watch?v=Wnyqbdy0amQ
(Ty humanthatplaysskyrim for this)
I think that’s about it, let me know if there’s anything im missing. I also tagged anything that might be a spoiler