Missing ingredient

I've spent most of today supervising a Sixth Form rehearsal of Macbeth, followed by a fun hour sourcing bloody daggers and the like on Amazon this evening. I feel I ought to be disappointed that this isn't poisonous.

The 'eye of newt and toe of frog' bit doesn't mention mushrooms or toadstools.

In actual fact, I spotted this fungi this morning on the way into school. I think it's a Japanese umbrella, but I'm not sure.

And yes, I know that I have taken a leaf out of Spiritedphotos' book... I hope he won't mind...