Lorenzo Saunders claims Oliver Cowdery met the Smiths in 1826.
Lorenzo Saunders, Letter to Thomas Gregg, January 28, 1885, rep. Charles Augustus Shook, The True Origin of the Book of Mormon (Cincinnati: The Standard Publishing Company, 1914), 134–135
READING, January 28, 1885.
Mister Gregg
Dear Sir. I received your note ready at hand and will try (to) answer the best I can and give all the information I can as respecting Mormonism and the first origin. As respecting Oliver Cowdery, he came from Kirtland in the summer of 1826 and was about there until fall and took a school in the district where the Smiths lived and the next summer he was missing and I didn't see him until fall and he came back and took our school in the district where we lived and taught about a week and went to the schoolboard and wanted the board to let him off and they did and he went to Smith and went to writing the Book of Mormon and wrote all winter.
. . .
He had an old glass box with a tile (spelling doubtful, C. A. S.) in it, about 7x8 inches, and that was the gold plates and Martin Harris didn't know a gold plate from a brick at this time.