In the first Life is Strange game you collected photographs, in Life is Strange 2 you collect backpack souvenirs. At the main menu there is a tab that features sketches that hint at the location of souvenirs. The following is a Souvenir Collectible Guide that will help you to find them.
Souvenir #1: Fishing Bait
While you are on the river you will stop and try to build a fire. From here, go to the tree on the edge of the area to find the fishing bait souvenir hanging from it.
Souvenir #2: Bird Feather
At the gas station, go to the back and find the pile of firewood near the jack-o-lantern. You will see a box in the tiny spot between the Halloween decoration and the pile of logs that you can interact with. Select to 'Move' it so the bird flies away and leaves the bird feather souvenir behind.
Souvenir #3: Bear Keychain
You will find the bear keychain in the gas station interior. Go to the counter inside and you will see a display with keychains to the left of the register. If you select 'Show' you will be given a the bear keychain for free.
Souvenir #4: Trucker Sticker
The trucker sticker is also found inside the gas station. Find the window next to the Halloween-themed advertisement and the fire extinguisher. There are trucker stickers in the windowsill which you can take.
Souvenir #5: Shark Tooth Pendant
On the seaside outside the Three Seals motel you will be approached by a dog. While playing with the dog throw a stick out toward the ocean. The dog will then bring you back a shark tooth pendant.
Souvenir #6: Three Seals Card
If you open the closet inside your motel room you will find the Three Seals card souvenir on a shelf to the right.
Souvenir #1: Metal Box
In the backyard, look up in the tall tree near the two-headed snow-man. When you look up at the metal box that is there you will get the option to ask for Daniel's help. Do it to get the metal box souvenir.
Souvenir #2: Sign
In the house, go up to the second floor and interact with the train set. Press 'Play', then use the Switching Station 'Turn Right' so the train passes by the Coaling Station. Select 'Prepare Refill' and then switch the switching station to 'Turn Forward' so it passes through the tunnel ahead. As the train passes through the tunnel you will hear a sound. After a few laps, interact with the main station to stop the train, and check it to get the sign souvenir.
Souvenir #3: Beer Cap
At Captain Spirit's house go to the backyard and check the snowman. There you will find a beer cap you can take from the snowman.
Souvenir #4: Spaceship
Go inside the house, and you will find Daniel talking with the kid next door. He will ask you to organize the toys - heroes on the left, villains on the right. You need to organize them perfectly to get the spaceship souvenir.
Heroes:
Pirate, Warrior, Dino, Bear
Villains:
Machine, Insectoid
Souvenir #5: Guitar Pick
At the Christmas Tree lot, you will meet a singing girl near the entrance. Wait and 'Listen' to her play. She will eventually start singing, when she stops you will be able to talk to her. Speak to her for a quick conversation. After that, she will get up and leave behind the guitar pick souvenir.
Souvenir #6: Bus Ticket
The last souvenir can be found once the brothers enter Karen’s room in the house. 'Look' at the CD Player and then 'Plug' it in when looking at the plug nearby. Try the CD Player again, and it still won’t work. When you then open the tray you will find the bus ticket souvenir inside.
Optional Sketch:
Walk over to the wooden log at the forest camp and sit down to sketch. Keep checking the different 'zones' after sitting down to complete the picture. When you do this optional activity you will unlock the 'American Graffiti' Achievement/Trophy.
Souvenir #1: Skull
At the small camp near the log where you can complete the optional sketch you will find a dog. When you select to 'Pet' the dog it will move to a new location every time you 'Pet' it. After 3 'Pets' the dog will dig up a small animal skull. This is the first souvenir.
Souvenir #2: Pen
Later in the episode, you will sit at a table with multiple characters as they cut plants. You will need to quickly cut 8 plants with scissors. Cut through enough and you will spot the pen souvenir in the plant pile.
Souvenir #3: Stick
Back at the camp, follow Finn when he rests at the base of a large tree. Select 'Speak' to talk to him. After the conversation, he will throw the stick he has been whittling. Collect this souvenir from the ground.
Souvenir #4: Fossil
Once you have completed your camp chores you will be able to visit Daniel at the lake. After skipping some stones you will be free to explore. Turn right, and look behind a fallen tree trunk to spot a strange looking rock which is the fossil souvenir.
Souvenir #5: Ingrid's Souvenir
When you return to the camp late at night you will be able to talk to various people as they party. Go to the lit tent and speak with Ingrid and Cassidy to get a tattoo. Before leaving for the lake, talk to Ingrid again. She will tell you that you are free to take anything from her tent. Go to Ingrid's tent and grab the souvenir out front.
Souvenir #6: Cartridge
You will be able to find the cartridge souvenir at the break-in area. If you are with Daniel, look for a yellow locker behind one of the pickup trucks. Daniel will open the locker for you and reveal the cartridge souvenir. If you are with Cassidy you will need to collect a tool from a nearby workbench to break open the locker.