Brant Gardner notes that beginning with the oldest high culture in Mesoamerica, there is a tradition of burying important religious relics. At La Venta the Olmec created a massive mosaic picture made of hundreds of serpentine blocks, and then buried it. Other offering caches included polished jade, concave mirrors of magnetite or other iron ores, and other items sacred to the Olmec. [Brant Gardner, Book of Mormon Commentary, [http://www.highfiber.com/~nahualli/LDStopics/Alma/Alma24.htm], p. 10]
“They Did Bury Them Up”
According to Daniel Ludlow, the converted Lamanites (Anti-Nephi-Lehies) refused to take up their arms against their brethren because, as they stated, "It has been all that we could do (as we were the most lost of all mankind) to repent of our sins" (Alma 24:6, 11). As part of a covenant with God they would give up their own lives rather than shed the blood of anyone else in time of war, they "took their swords, and all the weapons which were used for the shedding of man's blood, and they did bury them up deep in the earth" (Alma 24:16-17). It is entirely possible that this interesting incident could have served as the source of the "bury-the-hatchet" tradition of showing peace which was common among some of the tribes of American Indians when Columbus and other white men came to their lands. [Daniel H. Ludlow, A Companion to Your Study of the Book of Mormon, p. 210]