Interesting. Pretty amazing if it really belonged to Hezekiah. The "pagan" symbols have pretty profound implications for a King that allegedly cleaned up Judah:
2 Kings 18: 2 - 4 He was twenty-five years old when he became king, and he reigned twenty-nine years in Jerusalem, and his mother’s name was Abi the daughter of Zechariah. And he did what was right in the eyes of the Lord, like all that his father David had done. He abolished the high places, and smashed the monuments, and cut down the asherah, and crushed the copper serpent that Moses had made, for until those days the children of Israel were burning incense to it; and he called it Nehushtan.
But I gotta ask: Why would this be in a garbage heap?