Find a Lush Cave
Locate moss blocks naturally generating on the cave floor and walls
Break the moss blocks with any tool or by hand
Use a Silk Touch tool to collect the block itself
Use a hoe on moss blocks to break them faster
Trade with wandering traders for moss blocks
Use bone meal on moss blocks to spread moss and create more moss blocks
Craft moss blocks from 1 vine and 1 wheat in some versions if available through mods or datapacks