Don't know 'bout England, but the Northwest coast of America is frequented by the mugwort plant, mainly along the coastlines. It developed a pseudonym in the 1700's and was known as "sailor's tobacco". It is a close relative of the absynthe herb, wormwood. Nowadays, mugwort is often used in what are called "dream pillows", which stimulate one's dreams. Smoking it produces a gentle calm and a very mild buzz.

It has been said, that the original tobacco, so coveted by folks everywhere, was a mild hallucinagen, and that the cultivar we now smoke, is quite dulling by comparison.

I find it unrealistic to assume that Shakespeare wrote better under stoned circumstances. At least, it sure doesn't work for me. However, to intuitively put together a rough outline..., to laugh at the divine comedy... well,... what do you think?