it's not poison.... and yes it would be able to be tested for if they did that...but they don't, it's so uncommon for people to take that there is no commonly available test, only like a morg/forensics type situation would they really test for it and that is still only if they found some kind of evidence that psycadellics have been involved, and thats only in very extreme situations. and even if they did the psillisybin or psillocin would only be in your system for a very short period of time,mebey 3 days.
BUT THEY WILL NOT TEST FOR IT
i promiss, so don't worry
-cult
p.s. if in the future you ever have questions about any drug erowid.com is the place to be... i've used it for many years and if it weren't for erowid i would be dead by now...