Russula aeruginea otherwise knows as the Grass-green Russula, is an inedible russula

Russula

Around 750 worldwide species of mycorrhizal mushrooms compose the genus Russula. They are typically common, fairly large, and brightly colored - making them one of the most recognizable genera among mycologists and mushroom collectors...

 mushroom, found only under birch

Birch

Birch is a tree or shrub of the genus Betula , in the family Betulaceae, closely related to the beech/oak family, Fagaceae. The Betula genus contains 30–60 known taxa...

, mostly in pine forests; not rare.

Description

The cap is flat when young, soon funnel shaped and weakly striped; somewhat sticky and shiny, pale green to light grey-green, more rarely olive green. Often 5 to 8 cm
in diameter, sometimes up to 12 cm.
The gills are pale cream when young, later light yellow. The spores are dark cream.
The stem is white, occasionally with rust coloured spots at the base, often rather short with longitudinal furrows.
The flesh is white, brittle and without scent, with a mild taste.

Green specimens of the Crab Brittlegill, Russula xerampelina

Russula xerampelina

Russula xerampelina, also commonly known as the crab brittlegill or the shrimp mushroom, is a basidiomycete mushroom of the brittlegill genus Russula. Two subspecies are recognised. The fruiting bodies appear in coniferous woodlands in autumn in northern Europe and North America. Their caps are...

, can be mistaken for R. aeruginea.
However, one can easily distinguish the two, in that specimens of R. xerampelina always smell of cooked shellfish, while specimens of R. aeruginea do not.