Why do people hang baubles on Christmas trees?
Keep away bad spirits?
Distracts the Grinch?

PDF Downloads
As a Pro member, you will gain access to download any Instructable in the PDF format.
You also have the ability to customize your PDF download.
I think this idea was probably Germanic/Nordic in origin. Pagan beliefs which used to be considered an outrage by followers of Christianity, but eventually became accepted.
There are many different stories from all over the world. The origins are for the most part lost, and they are all sort of homogenous these days, but this is what I remember (vaguely) learning as a kid. Google is your friend at Christmas time. Ho ho ho.
If you've seen apples hanging on trees in winter, it makes sense.
+2
Another way to dry mushrooms is to put them in a sock, and hang this sock up next to your fireplace.
BTW, you can see/hear more about this cultural hypothesis, here:
The Pharmacratic Inquisition
http://www.sprword.com/videos/pharmacratic/
The part about amanita muscaria mushrooms and Christmas begins at about 58 minutes in.
The link where I found the picture of the Christmas tree with AM mushrooms on it:
http://theartofoneness.blogspot.com/2008/09/amanita-muscaria.html
Kids grow up with this every year, and it becomes ingrained-behaviour, that is what we do / what is done. So people do it every year.
L