Silver is found in nature as a free element as well as compounds because:
Silver is present in the middle of the activity series.
The elements which are present at the top of the activity series are most reactive. Therefore these elements combine rigorously with other elements and are generally found as compounds.
The elements which are present at the bottom of the activity series are least reactive. Therefore these elements doesn't combine with other elements and are generally found in free state only.
Silver is present in middle, that's why it is found in free state as well as compounds also.