In the past, a lot of vanillin came from the waste from paper mills. Recently, a Japanese scientist, Mayu Yamamoto, found a novel way of making vanillin. She extracted lignin from cow dung and converted that to vanillin. This discovery won her the 2007 Ig Nobel prize for chemistry, the send-up of the real Nobel prize.
—Simon Cotton, Chemistry World Magazine
—P.S. This apparently represents an improvement in vanillin manufacture. It’s typically made of crude oil.