Its common in the midwest and has a pretty flower but nothing seems to eat.Even in an over grazed pasture its untouched,bees an butterflies are attracted to it.What alternative treatment is it used for?

It's uses have been mostly for liver support.

http://www.erowid.org/herbs/milk_thistle/milk_thistle_info1.shtml

and

http://www.mothernature.com/Library/Bookshelf/Books/23/49.cfm

Scottish Thistle (Cirsium vulgare) and Milk Thistle (Silybum marianum) are not the same plant. Scottish thistle leaves are edible in salad, after spines are taken off (or it could be used as a "pot herb", see thread in Herb forum), and the roots taste similar to a Jarusalem artichoke, but I am unaware of medicinal value. On the otherhand, Milk Thistle is a wonderful medicine for the liver.
Lynn

http://montana.plant-life.org/species/cirsium_vulga.htm

Its amazing the uses of a single plant.

Some Cirsium species are grown as garden ornamentals.

For both ornamental and medicinal use, milk thistle (Silybum marianum) is better known. There is at least one clinical trial going on now to see if one of its compounds can be used to prevent or treat prostate cancer.
It has a reputation for treating liver problems, but claims in this area may have been overstated.