I - Where are the plates now?
He - In a cave, where the angel has hidden them up till the time arrives when the plates, which are sealed, shall be translated. God will yet raise up a mighty one, who shall do his work till it is finished and Jesus comes again.
I - Where is that cave?
He - In the State of New York.
I - In the Hill of Cumorah?
He - No, but not far from that place. (P. Willhelm Poulson letter of August 13, 1878 to Editor of Deseret Evening News, August 16, 1878)
It was likewise stated to me by David Whitmer in the year 1877 that Oliver Cowdery told him that the Prophet Joseph and himself had seen this room and that it was filled with treasure, and on a table therein were the breastplate and the sword of Laban, as well as the portion of gold plates not yet translated, and that these plates were bound by three small gold rings, and would also be translated, as was the first portion in the days of Joseph. When they are translated much useful information will be brought to light. But till that day arrives, no Rochester adventurers shall ever see them or the treasures, although science and mineral rods testify that they are there. (Edward Stevenson, Reminiscences of Joseph, the Prophet, and the Coming Forth of the Book of Mormon, 1877)
Attended meeting a discourse from W. W. Phelps. He related a story told him by Hyrum Smith which was as follows: Joseph, Hyrum, Cowdery & Whitmere went to the hill Cormorah. As they were walking up the hill, a door opened and they walked into a room about 16 ft square. In that room was an angel and a trunk. On that trunk lay a book of Mormon & gold plates, Laban's sword, Aaron's brestplate. (William Horne Dame, Journal of the Southern Exploring Company, 1854—1858, Iron County, UT, 14 January 1855, Della Edwards Papers, Special Collections, J. Willard Marriott Library, University of Utah)
See page 65 of the LDS Church Institute Manual
I wish to mention an Item of conversation with David Whitmer in regard to Seeing one of the Nephites, Zina Young, Desired me to ask about it. David Said, Oliver, & The Prophet, & I were riding in a wagon, and an aged man about 5 feet 10 heavey Set & on his back an old fashioned Armey knapsack Straped over his Shoulders & Something Square in it, & he walked alongside of the Wagon & Wiped the Sweat off his face, Smileing very Pleasant David asked him to ride and he replied I am going across to the hill Cumorah. ("Edward Stevenson Interview (1) 22-23 December 1877, Richmond, Missouri Diary of Edward Stevenson," LDS Church Archives, Lyndon W. Cook, ed., David Whitmer Interviews, 1993, p. 13; also Dan Vogel, ed., Early Mormon Documents, 2003, vol. v, p. 30.)