For your consideration, here is a 1978 Oregon State Samboree Corvallis Pinback Button, Pin, June 16 to 18.  It has some wear on it.  There is a little tarnish on the back.  The button has a diameter of 2 1/8 inches.  Item pictured is the actual item up for sale and comes from a non-smoking household.  (450.822y-.4px2)