This is my simple test, usually performed on purchased fungi, rather than wild gathered variety. First, does it have a tannish-brown to light orange cap? Second, does it bruise blue? Third, check the spore print color. Should be a nice purple-black. As far as I know, only fun-poison containing fungi (specifically psylocybe) carry all three of these characteristics. If someone knows better, please feel free to enlighten me however.
