Fraoch, or heather ale, is a legendary unhopped beer from Scotland, said to date back to Pictish times.
Calluna vulgaris. “Thomas Pennant wrote in A Tour in Scotland (1769) that on the Scottish island of Islay ‘ale is frequently made of the young tops of heath, mixing two thirds of that plant with one of malt, sometimes adding hops’. The use of heather in the brewing of modern heather beer is carefully regulated. By law, the heather must be cleaned carefully before brewing, as the undersides of the leaves may contain a dusting of an ergot-like fungus, which is a hallucinogenic intoxicant.” (Wikipedia) But if you live in the UK or elsewhere in its native range, nothing prevents you from just picking your own and, er, forgetting to clean it. There are also numerous cultivars. And heather honey is a thing.