There were several Sacred items that were buried with the Plates of Gold by the prophet Moroni:
"Having removed the earth, I obtained a lever, which I got fixed under the edge of the stone, and with a little exertion raised it up. I looked in, and there indeed did I behold the plates, the Urim and Thummim, and the breastplate, as stated by the messenger. The box in which they lay was formed by laying stones together in some kind of cement. In the bottom of the box were laid two stones crossways of the box, and on these stones lay the plates and the other things with them." (JS–H 1:52)
Oliver Cowdery, David Whitmer, and Martin Harris, saw these items at Fayette, New York, in June 1829 (see Doctrine and Covenants Section 17)
"Behold, I say unto you, that you must rely upon my word, which if you do with full purpose of heart, you shall have a view of the plates, and also of the breastplate, the sword of Laban, the Urim and Thummim, which were given to the brother of Jared upon the mount, when he talked with the Lord face to face, and the miraculous directors (Liahona) which were given to Lehi while in the wilderness, on the borders of the Red Sea." (D&C 17:1)
According to the LDS church, where are these items now?