"Yes, it does look like a Russula, and depending on the cap skin characters,
and taste (just a little bit on the tongue will tell you, and no, it won’t poison you)
can determine the species. In these really white Russulas, the cap skin will peel,
and how much toward the center, plus how rubbery it is determines whether it is
R. farinipes (slightly rubbery, peeling 1/4 to 1/3 of cap diameter) and bites back when
you taste it –quite hot and peppery; or if cap skin thicker, peeling at least half way or
more, it is probably R. crassitunicata. This sp. can have brownish spots of flecks on the
stem when older. It usually is a good sized sp. as your photo shows. R. farinipes generally
stays really white, has a more gracile (slender, more fragile) stature, crumbling more than
clean breaks, and has some cap margin striations, and is hot like cayenne peppers.
R. cremoracolor is also hot, larger like crassitunicata, cap peels a bit, and cap
surface creamy, almost yellowish, and stem firm but breakable, looking more dry.
Your photos are interesting and quite good. In the first one, the “line-up”
shows the peel-ability of the cap surface, and with the spotting on most of
the specimens thinks it R. crassitunicata. Your end specimen is some other species
and also probably a different genus too.
In close looks at the stipe, tho they are broken, the outside of them has the dry denseness
of R. crassitunicata as well. R. farinipes has a more watery-looking, almost translucent-looking
stipe surface, even when dry.
The only way to tell for sure is to use Melzers’ on the spores to compare drawings
of the spines and ridges between these, and look at the cystidia –
some have longer roots that go deep in the fleshing, showing their close affinity
with some of the Lactarius genus.
...stipe breakability questions. Russula stipes usually break like the blackboard chalk our teachers used – the fatter kind, not the skinny kind. But if weather is wet, then all bets are off, because the mix of cell types (both longer narrow hyphae plus the rounded, inflated cells that create its breakability, absorb a lot of water. But your photo shows that there are no long strings of hyphae, such as you would find in a Pholiota or Tricholoma. Some of the descriptive terms used in the keys are very general, and are not absolute for all species within a genus.