Good work on the block you made. Try your local library for books on 9/11. I have "September 11 - a testimony." It is all photographs, but you can get some ideas. There is one photo of the skyline from the water, with a the silhouette of a police officer on the ferry. Also, a photo of smoking trees bordering the field in Pennsylvania. Of course, you need a flag block and a "we will never forget" block.
Keep us posted on your quilt. And thank you.
Kris