Hiding in Plain Sight

Do you know the answer to this riddle?

 

I shift and change to match the scene,

blending in yet rarely seen,

My colors shift so that I can blend in,

they must think I'm one of them.

 

I live amongst you and go unseen.

 

The beginning for me was on a tree.

I dwell among you, trying not to be seen.

Search and search, yet pass me by,

hidden well from your eyes.

 

Look as you may, look as you might,

You'll find me hiding in plain sight. 

What am I?