Deadly Galerina likes to grow on dead conifers.
Death Cap grows on tree roots, not sure if that counts.
There aren’t a ton of mushrooms that grow on healthy living trees I think, so it’s kinda hard to find a poisonous example but maybe Jack O’ Lanterns count. They can grow at the base of living hardwood trees. They won’t kill you but you will have a very bad time. I think there’s another closely related species that grows on both conifers and hardwoods.
In addition to the previous gravy comments, namely that you absolutely must use some crumbly sausage textured protein and the associated fat, I’ve got something else to mention.
Perfect crumbly biscuits are so good and also so tricky to make, that I feel like there’s a slim chance you nailed it the first time, so keep trying.
I struggle to nail it and I’ve been attempting on and off for decades. What makes it difficult is:
if you over-work them (stirring more than ~12 times) and the ingredients become homogenous, the texture is ruined.
They’re still edible but nothing like the real deal.
If the ingredients get warm then the butter will melt and once again ruin the texture.
If you cut the biscuits wrong (e.g. twisting) the sides will “smear” together and they won’t rise right, ruining the texture again.
A perfect (buttermilk/crumbly) biscuit should be fluffy, crumbly, golden brown on the outside, white on the inside and have 10-20 little yellow butter “pearls” dispersed throughout it, something like tiny blueberries in a blueberry muffin.
Even knowing all that, I still find myself failing often and chasing that 5-10% of times when they came out perfect. That said, I’m shit at baking bread for some reason, just cursed it seems. Other people (grandmas notably) can just fucking nail it every time.
The gravy should be pretty easy: start with a generous amount of fat, lightly brown a little flour to make a slurry, add milk little by little until it’s thick like a chowder, add black pepper and “sausage” crumbles. You can always add more milk, NEVER ADD MORE FAT