Sketch - Erased Negative Space

The purpose of this sketch was to use only shading and erasing of any object that has interesting voids. I shaded the background and then erased the graphite to show the frame of the flowers. This sketch was pretty difficult because it was not easy to erase the graphite off. Therefore, it doesn't have a clean look to the drawing. What I would do to fix this is to erase the graphite more to show the figure clearly.