The firecap is a large mutated mushroom resembling a toadstool. Firecaps can be used to make a number of recipes, including the Forest disease cure, firecap soup, firecap tasty souffle, glowing fungus puree and are used in creating Mentats.
- Six grow in planters inside the Vault-Tec Agricultural Research Center - One on the main floor, and five downstairs. Oddly, these are not affected by Green Thumb.
- Up to five picked firecaps can be found on a concrete slab by the base support for the main, southwestern pylon of the Monorail elevator.
- Three can be found in a farm field near the I-59 and I-61 intersection. The farm location is on the image of a house on the main map
- Four can be found outside of the overseer's camp next to I-59 around Slocum's Joe, up to three next to the bus, one to the right of the building and one or two west across the river from the Nuka Cola billboard. Up to four more may be found around the pink house with yellow garage just south-southeast of Slocum's Joe, and more can be found along the railroad tracks east of I-59. From the pink house, head north along the tracks and keep looking left and right of the tracks. They spawn sporadically until you get to the second bridge. Under the second rail bridge is the last spawn.
- Two can be found at the Groves family cabin near a collapsed tree that blocks the road.
- One to four can be found around the highway in between the Gorge junkyard and Gauley mine exit.
- One to three can be found due south from the fast travel location at Marigold Pavilion.
- One to three can be found southwest of the Cow Spots Creamery, directly east of the I-59 sign on the map, on top of the hill growing on logs.
- One to three can be found inside the Arktos Pharma biome lab, on a planter inside a tunnel connecting Habitat A to Habitat C.
- One can be found on a log to the left of the church at Kanawha County Cemetery.
- One plant grows on a log on the side of the SH-91 due east of relay tower HN-B1-12. It is next to a truck with four Pulowski preservation shelters.
- One can be found when fast traveling to the Crosshair.
- One can be found southeast of the Overseer's camp.
- One can be found south of the WV Lumber Co., a short walk west of the spawn point.
- One can be found due north of Isolated cabin on a log.
- One can be found east of Moonshiner's shack on the tail of the cow icon on the map.
- One can be found growing on a fallen log west of Cobbleton farm.