Kurt Hockenbury sent over a link to the excellent "Chronicling America" archive of vintage newspapers at the The Library of Congress website. The collection includes scans of dozens of papers dating from 1860-1922. It's a great resource for anyone looking to recreate a vintage newspaper or clipping.
The period graphics and engravings are pure gold, but the text itself is just as valuable. One of the easiest ways to add an air of authenticity and depth to a prop is to tie it in to historical events, but add a Mythos spin to the story. After all, a clipping about a Federal raid on bootleggers seems innocuous...until you stumble across what really happened at Innsmouth.