David R. Seely discusses "silk" in the Book of Mormon; claims it is likely that "silk" was used for a New World cloth such as fibers from wild cocoons or a fiber from the pod of the kapok tree.
David Rolph Seely, “Silk,” in Book of Mormon Reference Companion, ed. Dennis L. Largey (Salt Lake City: Deseret Book, 2003), 724-25
Silk A fine, lustrous cloth. The word “silk” or “silks” occurs six times in the Book of Mormon, always together with “fine” or “fine-twined linen.” Among the Nephites and Jaredites silk was a sign of prosperity (Alma 1:29; Ether 9:17; 10:24), and along with Nephite COSTLY APPAREL, a symbol of pride and worldliness (Alma 4:6; cf. Jacob 2:13; Alma 5:53; 4 Ne. 1:24). Silk is also listed as one of the lustful desires of the great and abominable church (1 Ne. 13:7, 8).
Usually “silk” refers to fabric woven in East Asia from fibers spun by worms fed on mulberry leaves. Scholars believe this kind of silk was brought from East Asia to Europe by Marco Polo in the thirteenth century A.D. There is currently no evidence that this specific kind of silk was known in the Americas before the Europeans came. The term may be used to describe a number of different cloths known in the New World. It is likely that “silk” in the Book of Mormon refers to a fine cloth made from materials native to the New world. For example, early Spanish explorers recorded that the natives in Mexico gathered fibers from wild cocoons, a fiber from the pod of a tree (kapok), and a fiber of a wild pineapple plant, all of which were spun into fabrics described by the Spaniards as “silk” or “silk like.”
The word silk is used twice in the King James Version of the Old Testament, once to translate the Hebrew word sheshee, which was likely a fine LINEN (Prov. 31:22), and the other to translate the Hebrew word meshee, which likely refers to traditional silk.