Birdy, my first thought was the same as yours, so I googled it. As best I can tell, sandie only refers to pecan sandies when it comes to cookies. They started out as a brand name, but have been around long enough to refer to a type of cookie rather than a brand name. (Are we really that old? We ate these cookies when we were kids!)
What saves sandie as a potential addition to the list is that it is a golf term, also. When you either make par after having landed in a bunker or get out of the bunker and into the hole in two strokes, that is a sandie. There are two references to this use of the word on the very first page of the Google (US) search.
