Bunchberries are the impossibly red fruit of a low-growing dogwood variety, Cornus canadensis (for all practical purposes, these name should suffice - although there exist slightly different species with different names). They are of such a screaming red that the non-initiated certainly take them for poisonous. They are not!
In August, bunchberries ripen in the woods of Maine, and their beauty can't be overlooked; I always think they are sent from Heaven. They mix well and taste good with any other berry. Yesterday, we were berrying along a path deliciously flanked by branches laden with heavily with blackberries, and we had blackberries plus bunchberries "full" - so full that we decided to skip dinner altogether.
The blackberries'tart sweetness is well-known, they are very fruity, whereas bunchberries seem disappointing on first try. That is, if you try them alone. They are mealy and unassuming. But mix them in with blackberries or blueberries - and you don't consider them bland anymore: they shine. Their red color dazzles among the blue-black, and their taste and crunchiness are unsurpassed and satisfying.
The Native Americans used bunchberries to stretch their berry harvests and used them in pemmican, a mixture of berries, fat and dried meats (for protein) - a food that kept well, and was used for traveling and famine.
But bunchberry is more than a second-rate "ersatz" berry. It is considered an ant-cancer food (as are most plants that aren't poisonous, it seems). Once you have had the mix, you don't want to eat your blackberries without the bright red bunchberries ...