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[Glorfindel Goldtress]

In Letter 184 Tolkien explains that near Birmingham, (where he spent his childhood) "gamgee" (or "gamgee-tissue") was a colloquial local word for surgical cotton-wool, invented by Dr. Joseph Sampson Gamgee.
The "word pun" in the story is his linking together the families of Cotton and Gamgee .

That is indeed in the same notes Tolkien wrote for the foreign publications. I can send in PM to you the PDF of Tolkien's instructions regarding his nomenclature if you desire.