Back in January, I wrote a post about verified gnome-sightings in a city local to me. Now there have been verified troll-sightings (spotted beneath a local bridge -- where else would a troll be seen?)
The troll first appeared following the Loma-Prieta earthquake in 1989, after repairs were made to a section of the bridge which had collapsed. It is thought that the troll took up residence to bring good luck and protect the bridge from further disaster. There is also theory that, when the new bridge was being built, the project was plagued with problems due to the impending demolition of the old bridge span (which is home to the troll.)
If you like, you can read more about it here, here and here.