Beale,
This information can't be found online, as far as I know. I found this in old manuscripts when I was asked to do research for a Cal. treasure hunting group back in the 1980's.
It is very possible that Drake buried silver in the area of Cal., as witnessed by the text below.
Drake sacked Coquimbo which yielded many tons of silver. Then he decided on Callao, the port of Lima. There he found a fleet at anchor that contained "tons of silver bars, hundreds of golden ingots, boxes of specie, gems and pearls". The vessels were completely surprised by El Draco. Next, he learned that a very valuable plate ship had sailed for Panama two days before his arrival in Callao.
Drake gave chase, and eventually caught up with the heavily laden ship, the CACAFUEGO. The GOLDEN HIND fired one shot, which brought down the mizzen mast, and the Spanish commander gave up without any response. On board were " eighty pounds of gold dust, thirteen cases of royal plate, nearly forty tons of silver bullion, and three hundred bars of silver".
By now the GOLDEN HIND was so low in the water that the seas broke over her midships decks. So Drake headed for Cano island where he eventually dumped overboard 45 tons of silver. Before heaving the silver, he decided to award his crew with a share of what was left. Each man received sixteen (16) copper bowls of coins.
So there was a lot of treasure still on board when they sailed north.