Okay, there's a lot of letters out there, I took a few where you have to turn your head.
It's not alphabetical, and it's not complete, but it's better than nothing!
But here's the order:
I (turn your head.)
E (in the bars)
X
C
H
B
F (it's in the plants)
U
V
S (kinda slanted)
T
Y (turn head to the right)
W
J (turn head to the right)
A
O
Q (in the wires)

That's all I have so far, but I'm working on it.
(8 more to go)