If you know where to look, you can see it all over Innistrad. It's frequently seen on staffs.
Sometimes it's being destroyed.
Sometimes it's being used as a weapon.
Sometimes it's even made out of laurels.
The more you look for the Symbol of Avacyn, the more you'll see it. In fact, if you scroll back up to the top of this article and look at the art for Selfless Cathar again, you'll find another example beyond the obvious one. See the handle of the Cathar's weapon? Does the circle at the base look familiar now?