Its not a military accoutrement, as it is not an accoutrement given directive by the United States Army Institute of Heraldry. Meaning it is not prescribed for wear on any military uniform.
It is, however, a DOD-approved lapel pin, if that makes sense.
Its called a "Blue Star Service Banner"... Yours is the lapel pin version. They came to be back during the first world war... Believe it or not, the DOD treats it very similar to ribbons/medals that denote merit or valor... For example, the DOD has mandated guidelines for the manufacture, display, and wear of both the Gold/Blue Star banners and lapel pins. Only authorized manufacturers under American jurisdiction can produce them, and only under strict government license.
Blue Star - Family Members currently in military service to their country.
Gold Star - Family members killed while in service to their country.
Silver Star - (relatively) newly approved - family members injured in service to their country.
Assuming you do not yourself - It would be really awesome if you could clean it up some and find a close friend/acquaintance who has a family member on active duty... I'd rank that above a "class ring return"!
Nice find!
~Tejaas~
