The Battle Dress Uniform (BDU) was the military uniform that the armed forces of the United States used as their standard uniform for combat situations from September 1981 to April 2005. Since then, it has been replaced in every branch of the U.S. Military, and on April 30, 2008 it officially became unauthorized for wear in the United States Army. BDU-type uniforms still see active use in other nations, and are still worn by some police who may work in tactical situations, such as the DEA and SWAT. -- Wikipedia.
Here in Alabama, most of the new units I'm aware of standardize on Woodland pattern BDUs (Battle Dress Utility). This is true partly because it is cheaper and easier to find than other patterns (the thrift stores being loaded with them) but mostly because it is a good pattern year round for the South. (Yes, I know there are better patterns, but what we're talking about here is price and availability for newbies who lack funds.)
But BDUs, like everything else, wear out. I teach my newbies down here to recycle as much of the old uniform as possible.
For example, the first thing you should do is cut off all the buttons.
It is always a good idea to carry a couple of extra buttons in a small sewing kit for field repairs, and while you can pick up buttons for about $8.00 a hundred on line, there is no point in buying them if you can get them free.
I tell folks to save the cloth that is still serviceable for repairs. You can also make draw-string bags out of serviceable sleeves and pants' legs.
Some guys I know take the tattered cloth and make camo strips out of it, attaching them to harnesses, etc.