This is the most common Galerina here on the CA coast, and it looks like you have found the most southern sample of it, although that is probably because we haven’t gone to look for it in Monterey yet. It seems that anywhere on the coast where there is a mossy bed on the gound, this guy will pop up when it gets moist for a couple weeks.
As for the spores, these look about right, ellipsoid, with fairly rounded ends, uneven in profile, lightly warted, no plage, no germ pore. The size is a little small, I’ve measured ave. size from 9.8 × 5.7 to 10.3 × 6.1 um, but I think you are close enough? I wonder about your scope calibration a bit, or mine, I haven’t seen that much variation in spore size for these. Since this is so common, with spores like this, lightly warted, and the tibiiform cystidia, this is it. (If you want to go further, you can varify that the spores are non-dextriniod, and there are no pleurocystidia, and the basidia are 4-spored. Although those really have to be true given how common this one is, it would be interesting maybe to check?)
As for what type of spores define the genus, well for Smith and Singer at least, any type. There are sections in there with warted to smooth spores, with or without a germ pore, and with or without a plage, some dextrinoid, some not, and many they don’t record. And to add to it, they only provide drawings of a few spores (and those are fairly large, detailed, and a bit fanciful perhaps). The ones that are smooth with a germ pore are all pretty moved out to Phaeogalera by now, and I still haven’t seen one of those in CA, although there is probable one out there. These here are in the section of Tubariaopsis, and for the most part these are non-dextrinoid, lightly warted, without a plage, but not all, they all have tibiiform cystidia (in the sense of Gro Gulden, not so much Smith and Singer who define the section by lack of clamp connections, did you check that? These don’t have clamp connections…).
Anyway, that is the id. You’ve got enough here to be pretty sure about this id. (There’s more to this story, but this is probably enough for now…)
