- "Dogweeds" are daisy-like flowers in Thymophylla genus which are known to grow in regions of the U.S. and Mexico. "Deathcaps" are a poisonous fungus that can be lethal if ingested and is widespread across Europe. Interestingly, neither of these are actually known to be useful or have any particular lore about them (besides the fact that deathcap is toxic).
Notes and references
Baby Witch · Brews and Stews Café · Ceridwen's Cauldrons · Dervish and Banges · Dogweed and Deathcap · Dominic Maestro's · Hog's Head Inn · Honeydukes · J. Pippin's Potions · Madam Puddifoot's Tea Shop · The Magic Neep · McBloom & McMuck · McHavelock's Wizarding Headgear · Ollivanders · Pedrus Pridgeon · Rosa Lee Teabag · Scribbulus Writing Implements · Scrivenshaft's Quill Shop · Spintwitches · Three Broomsticks Inn · Tomes and Scrolls · Zonko's Joke Shop
Madam Rosmerta · Aberforth Dumbledore · Madam Puddifoot · Ambrosius Flume · Ambrosius Flume's wife · Dominic Maestro · Unidentified Ollivander's associate · Employee of the Owl Post Office · Archibald Bennett · Three Broomsticks waiter · Horace · J. Pippin · McHavelock · Scrivenshaft · Vladimir Plot · Zonko · Gwendoline Babcocke · Gwendoline Babcocke's mother