Unfortunately I would agree with the guy who said it is a reproduction. If you look at the below picture you will see the two coins are not just similar but identical - look for the small imperfections in the two coins and you will see how they match.
The coin pictured is a reproduction sold at this site:
http://www.google.co.uk/imgres?imgURL= http://www.greatamericancoincompany...f&imgrefURL= http://www.greatamericancoincompany...=0CCAQ9QEwBw
Also if you read the info on these reproductions it states that they are gold plated - if they are gold plated silver and your coin has been in the ground for a while and lost much of the gold then it would explain why one of the two people you showed it to thought it was silver and one gold. Odd though that they would have been using the same repro mould for 30+ years? Are you sure it was that long ago when it was found?
Its about time they stopped these people selling reproductions without 'REPLICA' clearly stamped on them - if your coin had sat in the ground for another 50 years who knows if it would be as easy to spot as a fake as quickly!