"This mushroom is known for the natural slice in its cap. Eating it fosters your competitive spirit. Use it when cooking to prepare a dish that will increase your strength."
The Razorshroom is a type of mushroom and material found in Breath of the Wild. This mushroom will restore ½ of a heart when eaten raw, but can be increased if Link decides to cook it into a Toasty Razorshroom over an open flame. Razorshrooms can be used in a variety of Recipes, and they have an extra cooking effect of increased attack. Razorshrooms can also be used to create Crimson Dye at the Kochi Dye Shop in Hateno Village.
Razorshrooms are most commonly found in the Ridgeland, Woodland, and Akkala regions of the world. They are most densely found in the trees surrounding Lake Illumeni in Ridgeland, and all throughout the forest area, just north of the Woodland Stable and east of the Woodland Tower.
Hyrule Compendium entry of the Razorshroom.