The excellent Lawyer's Wig - Coprinus comatus - is a rather common mushroom: I find it on lawns, verges and rough wasteland.
It's edible, although it tends to take on the flavour of other cooking ingredients, rather than adding flavour of its own.
The other day I mused about dependent species following their host. This concept is very clearly illustrated by Apanteles glomeratus, a Braconid wasp that is parasitic on some of the 'white' butterflies. The Large White and Small White butterflies became very scarce on my local patch, presumably because people had stopped growing their own brassicas: the Large White wasn't recorded in our 10k square for 10 years. However, as soon as I started growing Broccoli 2 years ago, both species were recorded on my vegetable patch.
When they're ready to pupate, they crawl up to the eaves of buildings and overwinter in their chrysalis. They start by making a web on the upper surface, and this is the instant that disaster can strike. The larvae of Apanteles glomeratus live inside the caterpillar, eating non-essential fat deposits, using the caterpillar as a mobile food producer. The instant the web is spun, however, they burst through the larval skin and pupate for themselves. The yellow cocoons are shown below:
Approximately 60% of this year's Large White larvae appear to be parasitised, which falls within normal expectations.
So although the host was missing for 10 years, the parasite is present only two years after the host returned.