Cube World Wiki, cataloging the cubes.
Woodland Scrub are a wild plants that can be destroyed to get Cobwebs. Desert Scrub and Fire Scrub are more akin to bushes and drop Wood Logs and Plant Fiber.
Cobwebs are used by Mages to make Silk to make light armor and Plant Fiber are used by Rangers to create Linen Yarn to create Linen Armor
The Wooden Logs can be used at a Sawmills to produce Wood Cubes which can be used for weapon crafting and upgrading Wands, Staffs, Bows and Crossbows.