Roy's caution is fully justified.
Under the microscope a look at the gill edge does make life simpler.
Stropharia caerulea has the dauntingly named cheilochrysocystidia. It's just a useful word to explain to those in the know that:
(1) The toadstool has specialised cells (cystidia)
(2) These cystidia have specific contents which usually give a
gold colour (chrysocystidia -
chryso as in
chrysanthemum, literally "golden flower"; and, less obviously,
chrysalis.
(3) These chrysocystidia occur on the gill
edge, which adds the Greek term "cheilo" to the mix, it means lip, edge or brim.
This is one of my "first generation" micro-photo's (back when I was using a Nikon Coolpix 4500) but which still gives an idea:
Stropharia pseudocyanea has very different cheilocystidia (gill edge cells) they form a sort of loose palisade of rather long cells with capitate (swollen) "heads":
It is these cells which give the distinctive contrasting pale edge to the gills, clearly seen with a x10 hand-lens.
Stropharia pseudocyanea has a useful field character - young, fresh specimens have a distinctive smell of pepper, though your specimen looks a bit too mature for this to be reliable.
I wouldn't like to make a definite identification here (in the absence of microscopical info), but given that as a self-confessed beginner you are wanting to extend your knowledge, and also to explore the biodiversity of the site I would suggest you call this "
Stropharia sp. probably
Stropharia caerulea; this is chiefly down to the lack of a contrasting pale gill edge as Roy has pointed out." This would be analogous to saying that a "Commic tern" had been spotted at ones local reservoir - still a useful piece of information.
Please do feel free to post here - and we'll try to explain the technical terms if they are necessary/helpful. They are, after all, just convenient shorthand - I remember when I was mainly a birder many years ago having to come to terms with supercilia, lores, scapulars, culmens, speculums, median coverts etc.!
Hope that helps
Chris
