Flameborn 
Plant Fiber
Materials Common Level 1 Raw material
Maybe they can be used as strings? They seem to be pretty robust.
Crafting
No known crafting recipe for this item.
Used in
39-
Bembel Pitcher -
Big straw mat -
Black Powder Ball -
Cat Pillow -
Crude Mattress -
Dog Pillow -
Explosive Barrel -
Fae Deer Food -
Fae Deer Food Bait -
Farm Animal Pillow -
Firefly Chandelier -
Firefly Lamp -
Firefly Standing Lamp -
Firefly Wall Lamp -
Goat Food -
Goat Food Bait -
Lantern Garden Gnome -
Marksman Boots -
Marksman Gloves -
Marksman Hood -
Marksman Trousers -
Marksman Vest -
Ornate Wooden Bed -
Paper Lantern (Short) -
Paper Lantern (Tall) -
Plant Fiber Roof Block -
Roof Tiles Block -
Room Divider Dragon -
Room Divider Fish -
Room Divider Flower -
Room Divider Snake -
Shovel Garden Gnome -
Shrub Seedling -
Straw mat -
String -
Sword Garden Gnome -
Torch -
Wax -
Wooden Bed
Source: see “Plant Fiber” on the Enshrouded Wiki (enshrouded.wiki.gg, CC BY-SA 4.0)