Could never get any coherent reply. Just let it be. I have a couple of fonts showing in the Trash that vary between Arial.ttf and TimesNewRoman.ttf. I think, these are Microsoft fonts. Any manipulations with FontBook or permissions have no effect on this behavior. But the fonts in questions are still on the hard drive and this does not visibly change anything.
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