1. Contact the Smithsonian. Seriously. I donated one of my midshipman uniforms to them many years ago, and they have a huge warehouse archive of military uniforms as they've changed over the years.
2. Contact a local military museum, especially one specializing in your father's years of service (WWII, Korean War, Vietnam, or other). It's not just the big cities-- each military base has a small museum, and many smaller towns have archives collected by local historians. If your father was a submariner then a local WWII submarine museum may be interested in his memorabilia.
3. Disney or other large movie studios. Again, seriously. When they invaded Oahu's Ford Island at the turn of the century to film the movie "Pearl Harbor", they unloaded container after container of actual WWII uniforms and other authentic gear. (Our local museums were going nuts with envy.) An entire floor of one of our training buildings looked like a clothing thrift store. Some of it was worn by extras while the more rare/valuable items were just salted about the sets for authenticity.
If one of those mementos is a Form DD-214 then it's a great source document for your family genealogist. I've considered mounting our family's DD-214s in a large frame but my spouse is not enthused about her contribution...