Except for the WWII version with silver in them, the US Nickel has been made up of 75% copper and 25% nickel - size unchanged since 1866. I have found V-nickels and shield nickels while metal detecting and they look exactly the same when in a roll with normal modern nickels.
The metal value in them I believe is currently over five cents. But as far as some Westward ones being different, I do not believe that to be the case as they have not changed the blanks that they use to mint them.
As far as saving them, it may be a good idea. I have read that some time in the near future that the nickels will be changed over to plated steel. I am guessing within the next two years.
Happy Hunting,
Scott (MI)