The shape you see on the blurry little lights in the background is the shape of the opening inside my lens. I had fun with it and changed it by cutting out a shape (pretty small) on a piece of paper, then holding the paper in front of and against my lens.
And we have Fall leaves! :) The darker edges are because my leaf was almost to small and my paper curled a little.
Aaaaannd, because everyone loves chocolate chip cookies...
I certainly wouldn't want shapes in all my pictures, but it's fun to play with!