buckwheat, herbal medicine
荍 is a rare kanji referring to buckwheat and, by extension, its use in herbal medicine. The two meanings are connected through the plant itself.
The exact historical development of 荍 is uncertain. It likely originated as a phono-semantic compound with 艹 (plant) and a phonetic component, but the original phonetic is not clearly preserved in the modern form.
The top 艹 suggests a plant. The bottom 收 looks like a hand receiving something. Imagine harvesting buckwheat by hand and receiving its medicinal benefits.
For キョウ, picture a person in Kyoto (京都, きょうと) gathering buckwheat for herbal medicine: Kyoto -> キョウ.