In order to get the correct coordinates, you will need to find the Quack Quack cache (GC4ZC66) which will have the info you need. In the Quack Quack cache, you will find values for ABC and DEF. Take those values and plug them into N 47 28.ABC by W 122 33.DEF for the correct Bonus cache coordinates.
You will be looking for a small camoed lock-n-lock. It is about 5 feet North of trail. It has a log book and a couple of trade items. The US dollar coin is for the FTF. Enjoy your visit and enjoy your walk and say hi to Donald Duck if you see him.
Congrats to TrekkingSloth and Boshea for your CO-FTF !!