These delicate little star-shaped flowers tick so many boxes... They are beautiful, beneficial, very easy to grow, and edible.
Borage self-seeds readily, and has few pest issues and pollinators love the little flowers as well - something about the way the flower is shaped - allows them to feed easily on the nectar. The plants themselves can become quite large and grow up to 80cm high, so give them a bit of room and they will look after themselves.
Much like comfrey, they are fleshy plants that are wonderful for kick starting your compost and for chop-and-drop mulching. Borage is also used as a green manure because it is a dynamic accumulator; the long tap root is able to draw up nutrients from deep within the soil and then return it to the top layer when the plants are cut and dug back in.
Most of all, I love to use borage in the kitchen. The flowers taste a bit like cucumber and are perfect for decorating salads, drinks and desserts.