Dandelions are my favorite flower. They can live almost anywhere: they grow in cool or in hot weather, in sun or in shade. You can eat the leaves: put them in salad or cook them like any leafy greens. (Some people eat other parts of the dandelion, but I have not tried that.) Rabbits and guinea pigs and bees like them.
If you use them for food, make sure that they come from a clean, protected area—not readily accessible to dogs, for example—and that has not been treated with pesticides or herbicides (nor with fertilizer that contains them).
You hear a lot about shortages of bees in some areas, and yet it is common to see people pull or kill dandelions in their yards and gardens; if more of the dandelions were allowed to grow, it would be good for the bees. If you truly have too many dandelions, instead of killing them with weed killer (which is bad for the environment and for the bees), just pull them; digging them out with a weed digger is very effective, but if you only pull off the visible, above-ground part, it will at least slow down future growth; or only pull off the flowers and seed heads to prevent reseeding. If you have a large yard, do not try to get every dandelion all at once (or weeds of any kind, for that matter); just work on it regularly—you will see progress. Personally, I like to leave many of them right where they are.
Dandelions in the wild.