When my characters find The Stoppable Force, I make a point of keeping it. It appears THe Moveable Object has been unfortunately removed from Retail, although it is back in TBCC - which isn’t enough for me to play it.
But, hey, what are your favorite gray-quality items?
lucky rabbits foot
Blinding powder after it stopped being a reagent!
“Once favored by rogues as a blinding agent, it was abandoned for more readily available resources… like dirt.”
Ooh, Broken I.W.I.N. Button is also another!
“If only it worked.”
the big big book o beards. A random drop from Grim Batol.
While I got no names, but I always fancied grey weapons and some armor pieces.
Enhanced Sours
Item Level 44
Binds when picked up
Requires Level 10
“May greatly improve performance in challenging dungeons.”
Been keeping them in my bags since legion.
anything that sells for more than 1k gold 
I fished a coin out of Dal once and I liked the inscription so I kept it. Still in my bank since… ehhhhh that was current content?
My rogue pickpocked a “rogue’s diary”… all the pages are blank. Can’t toss that out.
Stoppable force.
These two classics from BC:
https://tbc.wowhead.com/item=25402/the-stoppable-force
https://tbc.wowhead.com/item=25407/the-movable-object
lol I can link Wowhead but not TBC Wowhead, okay arbitrary forum rules
This is one of my favorites new to SL:
“What is a man? A miserable little pile of secrets.” - Dracula in one of the greatest 2D sprite based games of all time.
Ripped Ogre loin cloth.
LOL! That item is hilarious!
Some of these mentioned like the Lucky Rabbit’s Foot and the Stoppable Force might have some AH value in patch 9.1.
Among the new pets being added, there’s a new model. The one cost 10K pet charms, but the other 3 will sell for gray trash items;
Mommas lovingly worn wrench.
Saw Momma in mechagon and was like…‘yeah some guy who looks like me and using my name is hawking your tools…’
Always felt bad and vending them knowing that they are clearly engraved and the owner can be found. Heh
Pocket lint from the hinterlands quest. I farmed them one night when I was bored. I’d just joined a new guild, so i filled their entire bank with it. The GM messaged me and said “so this is how its gonna be huh?”
At least they saw the funny side.
I like all the gray items from beast mobs. I like to imagine the horror on vendor’s faces when some random adventurer forces them to buy some scraps of fur and some teeth we ripped out of the beasts skull. Or better yet, the skull itself. Or their feet. Like why do we just rip out a handful of fur and call it good?