Your Madison Dollar coin is one of the new Presidential Dollars released by the US Mint in 2007. The edge of these coins has an inscription that includes, among other things, the motto In God We Trust.

By design these coins can be either heads up or tails up when the edge lettering is applied. There is no extra value in the marketplace for the orientation of edge lettering, since both are widely available.

For more on the Presidential Dollars (which are not gold, but only a gold colored alloy) see:

http://www.valuable-coin-stories.com/presidential-dollar-coin.html

For more on the Madison Dollar, see:

http://www.valuable-coin-stories.com/james-madison-dollar.html