I can’t for the life of me get it. Where on the hanging lamp is it?
Odd. Did you put in 3550?
scrap that 
Viridian Room walkthrough here - with pictures!
Why can’t I pick up the trash can? I was able to before, but it won’t let me pick it up in this iteration (yeah, I started over again). This is very, very annoying.
Trash can: you have to “about item” on the hair before you can lift it.
I second this, where the hell is it?
It’s on the top left edge of the light as you look toward the door (and where you found that other card.) It appears to be camouflaged against the ceiling…all I saw was a tiny black outline. It seems to be as red as the ceiling.
It has to be facing the purple door, not the blue one. This vexed me awhile too.
The number that works for me is 5314