Howdy Ground-Fisher---
It looks like you have some work ahead of you - but it's the FUN kind of work. The first thing is to know what you have. A trip to Barns & Noble or Hastings would be a good start. They have reference books for just about every collectible. If they don't have it they can order it for you. For coins, a copy of the "Red Book by R.S. Yeoman", for military buttons and historical buttons,"Record of American Uniform and Historical Buttons by Alphaeus H. Albert", for military buckles/plates, "Plates and Buckles of the American Military 1795-1874 by Sydney C. Kerksis" . Once you have identified an item , you can usually get an idea of its value on e-bay. If you have trouble identifying an item, post a good picture of it on the "Whatzit" forum here on Findmall. There are some very knowledgeable people that visit that forum and there is a good chance that someone can help you. For additional information, there are websites dedicated to specific collectibles ; marbles, military wings & badges etc. If you plan to sell, aside from e-bay, garage sale, flea-market and gun shows are good venues. Also, attractively packaging your finds can increase the cash return.
I like ironsights idea about donating historical items! It's cool to visit the museum and see your name beneath the item!
Best of luck and...
Happy Hunting!
Blind Squirrel