FERN

Fern has no crafting use at all, no dye and no recipe that consumes it, so the only reason to buy one is the block itself: a patch of undergrowth for a build that is not sitting near the terrain that grows it naturally.

The trader is the sole villager source, at 1 emerald each, and getting it any other way means finding large fern in the wild and cutting it with shears. Punch it bare-handed and it drops nothing at all, which is exactly the kind of detail that makes an emerald feel cheap by comparison.

The Wandering Trader alone. He asks 1 emerald for 1 fern, a number fixed in the trade file rather than rolled, so any trader carrying this offer quotes the same price as the last one.

No profession touches it on either side. It is neither a raw material a Farmer wants back nor a decoration a Cartographer stocks, so this single trade is the entire villager economy around fern.

He asks 1 emerald each, and 30 of the other 75 come cheaper. Price is the easy part: he draws his stock from a shared pool, so catching one that happens to be carrying fern is the real constraint.

The Wandering Trader asks 1 emerald for a fern. 8 of the 72 villagers that pay emeralds, emptied out:

a jungle boat against 26 flint for the same 1 emerald, 26 times the carrying, and the shortest wait is the Butcher at 37.5 real seconds of shelf, gathering not counted.

There is no village behind this offer, so village mechanics do not apply here at all. The trader shows up on his own near you, two leashed llamas in tow, stays roughly forty minutes to an hour, and leaves again whether or not you traded, with no workstation to place and nothing to break that would change his stock in any way.

He will not buy fern back either, under any circumstance. Only six specific items ever move from a player into his inventory, a fixed short list that this decoration is not part of, so the trade only ever runs emeralds out of your inventory and fern into it, never the other way.

What he happens to have is a partial slice of a much bigger list, so a given trader may simply not be carrying fern that visit, no matter how long you wait around. Naming one that does with a name tag stops the despawn timer for good, which turns a passing encounter into a spot you can come back to whenever you like.

Decorating a build is really the only reason to spend 64 emeralds across 64 trades on this. If you already carry shears and happen to pass the right terrain, cutting it directly costs nothing; the trader only earns his keep when neither of those is true.

Look over the rest of his stock while he is nearby. Also on his list that visit: sugar cane, pumpkin, dandelion, poppy, blue orchid and allium.

A fern drops nothing when broken by hand and gives no seeds, so shears are the only way to collect one. That single fact is why a trader selling ferns is selling something a player often cannot be bothered to gather.

It grows in taiga and jungle, and the large version can be split with a stroke of shears into two ordinary ferns. Bone meal turns a small fern into a large one, which is the only growth step it has.

A fern is one of the better things to throw in a composter, and since it is free wherever it grows, a taiga is effectively a bone meal supply for anyone with shears and patience.

Bone meal on a fern grows it into a large fern, and shears on a large fern give two back. That is the only way to increase the number you own without going and finding more.

In a build it does what grass cannot: ferns read as woodland floor rather than lawn, which is why a taiga or jungle interior looks wrong without them.