Growing in Pinus radiata duff.
Seen fruiting on the forest floor of this mixed oak-bay woodland. The diameter of this wavy cap is about 45 mm and the stalk length of this gilled mushroom is around 40 mm.
I think it's this one:
The Russulaceae are a family of fungi in the order Russulales. According to a 2008 estimate, the family contains 1243 species. Its species typically have fruit bodies with friable, chalk-like stalks, that break with a distinct crack, somewhat like a carrot but with porous flesh (see below). Microscopically, the cells are not all long thin hyphae, which would provide strength and more fibrous appearance when broken. Instead, the flesh contains also many large spherical cells ("sphaerocysts"),...