The Adventures of Tom Bombadil actual translation from the "Red Book of Westmarch", and contains some background information on the world of Middle-earth that is not found elsewhere: e.g. the name of the tower at Dol Amroth and the names of the Seven Rivers of Gondor. There is also some fictional background information of those poems, linking them to Hobbit folklore and literature and to their actual writers (some of them are ascribed to Samwise Gamgee). The book uses the letter "K" instead of "C" for the /k/ sound in Sindarin (one of the languages invented by Tolkien), a spelling variant Tolkien used many times
Brandybuck Clan stated to be a rendering of the original Westron (Common Speech) Brandagamba, "Marchbuck". In keeping with the conceit that "The Lord of the Rings" was derived from the translated Red Book of Westmarch, Tolkien claimed to have translated all its Westron words into English — including the names of characters. While "Marchbuck" ("march" bearing its archaic meaning of "border") is the exact representation of "Brandagamba", Tolkien rendered it "Brandybuck" to preserve the name's similarity with the River "Branda-nîn" ("Baranduin" in Sindarin), which Tolkien then rendered "Brandywine" in English to reflect an alternate name, "Bralda-hîm", meaning "heady ale", referring to the