You find a run down community building and learn that it was a place where inhabitants were waiting out the eminent doom of the world while everyone succumbed to rioting and looting. Its a gymnasium kind of look to it and above the bleachers in a nice red sign it gives the words of advice: DON'T PANIC!

-Hitch hikers guide to the galaxy.

Or you can find this on a towel rack in a prewar home.

That would be pretty cool. Maybe something like a messenger sent to the capital wasteland to say there will be a new leader of the brotherhood in DC, but they were killed along the way and the note is in their hand......

Uhh, seriously? No. Enh. Oh.
Do you really think that anybody would send someone to get to the other side of the states ON FOOT just to make him say "Hey, wasteland scum! There is a new Elder in the DC, and you better respect his authoritah!"

A Friendly gecko named Smurloc or something.

Nucular, it's pronounced nucular,