What happens if you eat a deadly galerina?

Deadly. Contains amatoxins identical to those in the death cap, with the same delayed onset and liver failure. A small quantity is sufficient.

Deadly Galerina vs Honey Fungus

The test that settles it

Honey fungus has a white spore print. Galerina's is rusty brown. Always take a print before considering anything clustered on wood.

Never eat a wild mushroom identified by a website or an app.That includes this one. These tools narrow possibilities; they cannot see your mushroom, its base, its smell or its habitat, and the difference between a meal and a liver transplant is sometimes a feature buried in the soil.
Get it confirmed in person by an experienced local forager or a mycological society. Most regions have one, most run free identification sessions, and they will look at the actual specimen.
Dig, do not pull. The cup at the base of a death cap is often underground. Pulling the mushroom leaves the most important feature in the soil.
If someone has eaten a wild mushroom and feels unwell, call poison control now — in the US, 1-800-222-1222. Do not wait for symptoms to worsen. Amatoxin poisoning has a false recovery phase, and delayed treatment is what makes it fatal. Save any uneaten pieces for identification.

Can kill

Galerina marginata

Under the cap: gills
Spore print: rust, brown
Growing on: wood dead, conifer litter
Stem: Slender, brownish, with a thin ring that is easily lost, and often a whitish fibrous coating below it.
If eaten: Deadly. Contains amatoxins identical to those in the death cap, with the same delayed onset and liver failure. A small quantity is sufficient.

Causes illness

Armillaria species

Under the cap: gills
Spore print: white, cream
Growing on: wood dead, wood living
Stem: Tough and fibrous, with a whitish ring, growing in dense fused clusters.
If eaten: Causes gastric upset in a significant minority of people even when properly cooked, and must never be eaten raw. More importantly, it shares habitat with the deadly Galerina — this is a genus where a spore print is essential rather than optional.

Rusty brown spore print — take one, because this separates it from most of what it resembles.
Grows in clusters on dead wood, especially rotting conifer logs.
Thin ring on the stem, often smudged with rusty spores.
Small and nondescript, which is why it gets picked by accident.

White spore print. Take one. This is the difference between honey fungus and a lethal Galerina.
Dense clusters fused at the base, on or around stumps and living trees.
Ring on the stem and fine dark scales on the cap.
Black bootlace-like strands (rhizomorphs) often visible under nearby bark.

Then you have your answer, and it is not to eat it. Run the full key, then take the specimen to someone who can hold it.