can you turn all sorts of threads (fate, thought,etc.) into silver?
i have a large stash of them collecting dust in my home.
To answer both of you at once:
Yes, you can turn in all three types, and each one is worth 100 silver each, no matter the type. If you've ever been to your faction base and looked in the chest, you'd already know this!

It really isn't secret information.
I'd consider holding on to them though, you never know what the devs might do... remember what they did with blackrock. Once everyone turned in their large pieces for rewards, a few months later, you needed it for something else ( casting ). Who knows when the ghosts of Magnicia will finally rest in peace, and the city rebuilt? They may become collectors items, those threads.