I remember when I was a little girl shortly after WWII having to have
red or green mills which round shape as tax for items bought.  For
example a bottle of milk was .10 plus a red or green mill   Does
anyone have information about how this was started and if mills are
part of an archive or are collector's items

Mills?  Were these food coupons?  Which country?

Ladycoy, take a look and see if these Office of Price Administration
tokens are what you remember:

http://www.coinworld.com/news/081803/bw_0818.asp

These tokens are small, about the size of a dime or less. They
actually were "ration" coupons, not exactly a "tax," but close. I
haven't heard them referred to as "mills" before, but I'm a little
younger than you, so I don't any personal knowledge to rely upon, lol.
I'm not giving a comprehensive answer, but this might help a
researcher focus on your specific request (whether or not these are
the items you are seeking). Good luck.