I like the idea of gold pinecones and lots of texture. At first I thought to stencil a Celtic symbol on the pot, but then realized it would be too time-consuming for the $. I would use your moss on top instead of on the pot, but I would rub the pot with gold so the terra cotta shows thru. There is a great product I have gotten at Michael's that comes in a little tube and you can just rub it on--looks good. I would tend to intersperse gold elements and terra cotta colored flowers with the moss, but I tend to like a compact look.
The Celtic element really throws me for a loop. What's that about? Is the school oriented that way or is it their theme for this event?
I miss Michigan! Why aren't they using copper?? (For those who don't know Michigan, the area where she is is referred to as Copper Country for the old copper mines there).