Symphytum asperum, Boraginaceae
If you are interested in attracting more pollinators to your garden, especially bumblebees, grow some comfrey, rough comfrey in the case of these pictures. In the few minutes I spent around this colony growing along the river Clyde I took a dozen shots of different bumblebees (of which these were the best as I should ditch my phone and switch to a decent camera). No other group of plants in bloom in the surrounding area was experiencing the same amount of insect activity.
Aside from being clearly beneficial to the bees, comfrey - a number of species within the Symphytum genus - has also been used as an edible plant (which can cause damage to the liver over time so I wouldn’t really use it that way) and as a dynamic accumulator. The latter expression means that comfrey is one of those plants which send down a deep and robust set of taproots and gather nutrients in the leaves. This phenomenon is useful in two ways: as the root system draws water and nutrients upwards, nearby plants get to enjoy the effects of capillarity, at least to a certain extent depending on their distance, while the large leaves can be periodically harvested throughout the growing season to be added to the compost box or turned into liquid fertiliser.
Comfrey is often mentioned in permaculture design, and generally positioned below the drip line of orchard trees, where its qualities are most useful.