Spore blossoms were introduced in Minecraft 1.17 as part of the Caves & Cliffs update. They will be fully integrated in Minecraft 1.18 and are available to all without any outside help.
The lush cave biomes are only currently available in Survival Mode in Minecraft Worlds. If the custom or buffet type is selected in Java Edition then Survival Mode will fully generate in Minecraft 1.18. It is also possible to find it for Bedrock players if experimental gameplay has been toggled active.
After the update, Survival Mode players will be able to access spore flowers and other flora found in lush caves.
Although the bright pink spore flowers are found in lush Minecraft caves, little else is known. They can be broken with most tools, by hand, or by shears. This reduces their durability but does not provide any additional benefits. Currently, spore blooms are only found in their home biome. They cannot be found anywhere else in Survival Mode.
You can place spore blossoms on any block in Minecraft, except leaves. As they hang, they emit green particles that can spread in the open and surround the spore bloom in a limited radius. Other than these unconfirmed facts, little else is known about spore blooms.
Concept art for Minecraft's Caves & Cliffs Update Part 2 shows that spore blooms can open and close. This is not clear and the concept art doesn't guarantee that any closing spore blooms will make it into the final build.
Mojang will be providing additional information in the days ahead. Minecraft players will have to wait to see. It is possible that there are crafting recipes and other uses for spore blooms that aren't yet obvious. Although the plant might seem innocuous for decoration, Minecraft is known for its ability to provide more utility for a wide range of items and blocks.