Pin from Atomic Ashes - what is it?

Pin from Portland

This pin came from the $2 tray at Atomic Ashes in Portland. I love it. What is it? I can tell it's a primary pin that had add-ons; the crest is a 2nd year accoutrement, the blue banner is 3rd year and the white banner is 4th year.

I don't know what the Presbyterian SS is but maybe I want to join if they give out pins like this?