I never heard of the dram tree in the USA but there is a story regarding a "Dram Tree" in Ireland.
A few years ago I was doing a tour in Ireland with a folk music group and we stopped somewhere in the midlands at a cafe for tea. Thew cafe had been converted from a whiskey distillery when the distillery closed. As they were dismantaling the copper vats a copper pipe was discovered running from the bottom of one of the largest vats. They followed this pipe out of the building, across the road and found it emerged in an old hollow tree with a tap (faucet). In the hundred years or so of its whiskey manufacture the owners never knew that the locals had a free suppply.
Bill