is created by the system and is usually generated as a response to a crash or sudden shutdown (power loss, for instance)
The system hangs on to those files, they are not always fonts, just in case it needs them when the reboot happens.
If the reboot is a success, then the system moves those files into a folder, Recovered Files, and puts them in the trash.
It is quite safe to empty the trash. Any files in the trash cannot be used by the system, or anyone else.
After every reboot or restart, I just started seeing a new file named "Recovered files" in the trash containing fonts. All fonts in there are system fonts. I remember this happening in OS9 but I never had this in OSX before. I close all apps before shutting down.
OSX 10.5.8 Dual 2.3 GHz PPC G5 5 GB DDR2 SDRAM NVIVIA GeForce 6600 256 VRAM