My family found historic gold, what should we do?

LONG READ BUT DEF WORTH IT! Ok last week my sister and I found a map about 5 feet under the ground in a field close to our home. The map was in a brown case with writing on it in different language. So we took the map home and showed it to the family. It looked extremely old, and soon we found that it was a map of our home town. There were places pinpointed, so we decided to take the car and drive to those places. Once we got there, there was a sort of monument which was half broke, and on it it read 'those who dig the furthest will find the throne, up the hill and behind the stone'. We didn't know what it meant but something clicked to mind and I said it couldn't be 'The Stone' could it?' So we decided to journey to the place known as 'the stone'. When we got there we had to drive the car to the top of the hill in order to reach the stone. The stone was there alright but it was too big to move on our own. We decided to dig around one side of it so that the stone would fall to one side. We finally got it moved after an hour or two and behind the stone was a cave. We entered it and seen the was nothing there, and thought this was a waist of time, but then we remembered what the monument said ' those who dig the furthest will find the throne', so we decided to dig for a while. We dug for about 4 foot and found nothing but we had to keep digging, an hour later we dug to about 8 feet and heard an noise when we hit the shovel to the ground. So we got on our knees and scd the dirt away and you wouldn't believe it but we found gold and lots of it. Things that seemed hundreds of years old. There must have been about 50 pieces of gold, so we packed the car and we had to come back for the rest as there was too much. It is now sitting at our home, but we don't know what to do with it, should we keep it, sell it or tell authourities or something as this is very historic pieces of gold!