A friend of mine at work was on an archaeological dig in Portugal. He found a copper coin that he says resembles the Alphonso V (1438-81) coin on this website. http://home.eckerd.edu/~oberhot/1453.htm I know it's hard to say a value without a picture but are these coins worth anything or are they common? He is going on vaction for a few weeks. I will post a picture when he gets back.
It should be a "Ceitil" (1/6th of a Real), the local "Lincoln cent" of its time... Certain types are rare, but common and low grade specimens of those sell for a couple of euro, only with pics with be possible to give you an idea of the coin value. Jose