Is it Trash or is it Treasure?

Does anyone else out there love their trash? Craft projects are always popping up where I need that precious piece of trash I just threw out.

I definitely find myself holding onto things I should probably send on their way. However anytime that particular piece of junk is used... It only strengthens my resolve to hold onto all the junk...all the trash.

What are your favorite crafty/junky keeps? Mind is cardboard. I just can't let that perfect box go.