Grass
From Eco - English Wiki
Grass (also called Common Grass in-game) is the most widespread plant in ECO, growing on the majority of grassland blocks upon world generation.
Players can use the Scythe to harvest grass for a chance of receiving Plant Fibers.
Common grass will spread naturally but cannot be replanted, since it does not drop seeds. For a more systematic way of farming plant fibers, Bunchgrass can be farmed.