I’m partial to wriggling goop.
for some reason i keep all the empty Brew of the Month bottles. some of my older alts have more than 3 stacks
I keep 3 on my huntard.
Broken I Win Button, Broken U Lose Button, and Vial of Tears.
Going with the classic, The Stoppable Force.
I like to carry around Smelly’s Luckydo and Potion of luck.
Bad Troll love poem.
I refuse to sell it.
Fragile Model of Stormwind Keep.
For… reasons.
Beat me to it.
My precious old Totem of the Earthen Ring
DH when they get nerfed
DH when they get nerfed.
A dead mole. 
All trash items you get in Archaeology. They sell for a ton and have story to them.
Least liked are the Nightborne coins. They don’t stack.
Just for the goofy face.
Also this one, for the flavor text: “Such color. Many shine. So heavy. Wow!”
I usually keep at least one of the pickpocketing greys from each expansion. The rest I mail to guildmates with zero context.
And of course all Steamy Romance novels.
Steamy romance novels, ahhh who am I kidding I trade them to others to read.