Q:

What items are 100% totally useless when you have all DLC?

All the lists I found include things like Coffee Mugs which aren't actually useless because you can give them to Muggy. I haven't found any lists that are up-to-date for all DLC. 
What items can I definitely throw away? I.E. What items can't be used for crafting, can't be traded with NPCs for useful items, and aren't used in quests?

A:

Here's the list of completely unusable items (which means they serve only decoration purpose - no crafting, quests, dialogues, nothing else). I'm not 100% sure the list is complete (maybe 99%) - there might be an error or two.
BASE

10 Ball 
13 Ball 
2 Ball 
5 Ball 
8 Ball 
Acoustic guitar 
Ashtray 
Baseball 
Baseball glove 
Basketball 
Bent tin can
Big spoon
Brahmin skull
Brotherhood of Steel holotag
Centaur blood 
Chessboard
Cigarette 
Counterfeit bottle cap 
Crutch 
Cuddles' toy car 
Cue ball 
Cup 
Cutting board 
Damaged garden gnome 
Deathclaw hand 
Dinky the T-Rex souvenir 
Dino toy 
Dog bowl 
Doggie treat 
Drinking glass 
Empty jet inhaler 
Evil gnome 
Finger 
Garden gnome 
Gecko egg 
Golden gecko egg 
Golf ball 
Hammer 
Harmonica 
Infected brahmin meat 
Intact garden gnome 
Lawn mower blade 
Leaf blower 
Motorcycle gas tank 
Motorcycle handbrake 
Mutilated arm 
Mutilated leg 
Mutilated organs 
Mutilated skull 
Mutilated torso 
Nuka-Cola truck 
Ophthalmoscope 
Paint gun 
Paperweight 
Ping pong ball 
Plunger 
Pool ball 
Rake 
Scissors 
Sheet music book 
Shot glass 
Spatula 
Spork 
Sunset Sarsaparilla deputy badge 
Tanned gecko hide 
Toy car 
Triangle 
Vacuum cleaner 
Whet stone 
Wood chipper 

DEAD MONEY

Embalming fluid
Gold bar

HONEST HEARTS

Green gecko eggs
Scripture

OLD WORLD BLUES

Broken detonator
Deactivated bomb collar

LONESOME ROAD

Seymour
Tunneler hide

