White and gray are safe to eat, black is not. White purifies you, grey neutalizes you, and black I can;t remember because i never eat them. If you are trying to get a permanent state then do not eat unicorns, it removeseven perma states. On the other hand if you found a ring of polycontrol and just drank from every fountain form UT1-GC8 and ended up permaslowed and permaconfused then seek ye out a unicorn.
I also find that the best way to deal with magic mushrooms is to kil them and eat them so that they do not re-spawn. Unicorns could come in handy here too.