I've still got the flag that flew on my car antenna immediately following that day. I got the flag by donating to the Red Cross. They were handing them out. The flag eventually got tattered, so I took it down, and it's packed away in a box of keepsakes. Tangible, physical evidence to mark that sad event.
I no longer fly a flag on my car--they take such a beating. But there's a lovely full size American flag flying proudly every day in my front yard :-)