It's one of the first flowers to greet the early bees and butterflies venturing out in the spring. From March to May, they're covered with flowers—when few other pollinator-friendly flowers are out. Other pollinator-friendly flowers like Rudbeckias (Black-Eyed-Susans), echinaceas (Coneflowers), zinnias, Bee Balms, marigolds, etc. won't join the parade until summer.
Butterflies, ladybugs, honeybees, bumblebees, even fireflies eat the nectar from the flowers, while goldfinches and sparrows like the seeds. Rabbits and chipmunks nibble on the greens. Hoverflies, an important predatory insect (their larvae eat vast quantities of aphids) love dandelion nectar.
They are actually good, long-term, for the soil. Their long thick tap roots not only bring nutrients to the surface, where they are more available for other plants, but they help to aerate compacted soil.
