Check the dates and town of manufacturing on those coke bottles. A few years back I drove an hour into New Hampshire to a farm where I bought a box of antique bottles out of a barn for 20 bucks, they were never in the ground. One of the bottles was a DEC 25 1923 "Christmas" Coke bottle, but that's not what made it super rare. The town where the bottle was manufactured was the key as, according to the price guide, there is less than 10 known examples. I had collectors from all over the country bidding on it on Ebay.