What Cavern Mushroom Is For

Treat it as a raw material, not food — 15 satiety is nothing, and everything that consumes a Cavern Mushroom consumes it by the dozen. Two lines matter: the recovery meds tree and Mushroom Cake , the breeding cake that adds +1 to +5 to a hatchling's IVs.

• Mushroom Cake — 3 per cake, alongside 5 Mushroom , 5 Flour, 8 Eggs and 2 Honey. The Breeding Farm eats one cake per egg, so any breeding project measured in hundreds of eggs is really a mushroom project.
• Recovery meds — 3 / 5 / 10 / 15 as you climb from Low Quality Recovery Meds to Advanced Recovery Meds , and 30 for a single Revival Potion , the only item that revives a downed Pal in the field.
• Everything else is small — 10 per Nutrient Tonic , 5 per Pal Recovery Grenade , 1 per Alluring Bait (three baits per craft).

Mushroom Cake is the cheap IV cake, and that's what makes mushroom supply worth solving properly. Extravagant Vegetable Cake carries the same +1–5 IV bonus with +2% mutation chance on top, but it wants plantation crops and Cotton Candy for every single egg. Mushroom Cake's two mushrooms both come off one Pal standing on a Ranch — it's the IV cake you can bake by the hundred.

Where It Comes From

• Caves and dungeons. They grow in clusters underground and are picked by hand. There is no seed for them, so no plantation will ever grow one — hand-picking is fine for your first stack of meds and scales to nothing after that.
• Shroomer on a Ranch — the renewable source. Its partner skill, Rampant Spores, periodically drops either a Mushroom or a Cavern Mushroom while it works a Ranch, so one Pal covers both halves of the cake recipe. Drop size scales with the Pal's rank: an unstarred Shroomer drops exactly 1, a 4★ rolls 1–5. It has Farming 3, so it assigns itself to the Ranch without any fiddling. Wild Shroomers roam the Sakurajima mushroom wetlands and the rocky ground north of them, day or night.
• Don't use the dark variant. Shroomer Noct looks like an upgrade and isn't: its Roiling Spores skill only slows SAN decay for base Pals. It produces no mushrooms at all.
• Expeditions — the bulk source. Blazing Cavern and Hidden Sanctum of the Desert each pay a guaranteed 4–8 per 45-minute run before the reward multiplier; Free Pal Alliance Illicit Trading Post pays 10–20 over two hours. Verdant Hollow and Secret Realm of the Forest roll Cavern Mushroom against plain Mushroom in the same slot, so only about half their runs pay out (2–5 and 3–7 respectively).
• The Legendary Grocer caravan also sells it for gold.

How to Get Plenty of It

1. Build a mushroom ranch, not a mushroom trip. Ranches have no per-base build limit, so a breeding base can run several side by side, each staffed with Shroomers. It's the only mushroom source that keeps producing while you're away, and it covers both mushrooms the cake needs. Park a Beegarde on the same Ranch for the Honey and let a Mill handle the Flour, and the cake line runs itself.
2. Condense your ranch Shroomers first. Stars on a producer are worth more than stars on a fighter here: going from unstarred to 4★ turns a flat 1 per drop into 1–5, up to a 5× swing on the same Ranch slot, and Shroomer is common enough that fodder is cheap.
3. Breed Ranch Master onto them. Farming rank governs how fast a ranch Pal produces, and Ranch Master adds +2 ranks ( Farmhand adds +1). Work out the line with the breeding calculator.
4. Cap the expedition multiplier before you farm with it. Expedition rewards scale to a hard 10×, which turns Blazing Cavern's 4–8 into 40–80 mushrooms per 45 minutes — more than a ranch produces in a day, for Pals that were idling in the Palbox anyway. The expeditions guide covers how to reach the cap, and the expeditions page has every site's full drop table.
5. Decide up front whether a stack is cake or medicine. One Revival Potion costs 30 mushrooms — the same as ten Mushroom Cakes, and no merchant sells the potion, so it only ever comes out of this pile. Merchants do sell the lower meds tiers, so buy those rather than crafting them and keep your own mushrooms on cakes.