I have found a driver's license. How will I be able to return back to the owner?

I would call/take it to the police station or DMV. (P.S. I don't think the police respond to these)

There's an address under the owner of the cards name ie 146 2nd Street Moscow Idaho, drive your vehicle to 146 2nd st, in Moscow , get out of your vehicle without falling, walk to the door with said license look at picture on license and the person at the door so you can verify they are one and the same...I would gladly give you your license back. ,, thanks have a great night!