Dandelions are often considered the scourge of most gardeners. Their fluffy, yellow flower heads may look quite attractive but once the heads turn to seed, the slightest puff of wind spreads dandelion seeds over the whole of the garden. You could try digging them out but they have a long, tapering tap root which tends to break off as it is pulled. You only have to leave the smallest part of a tap root behind in the soil and you will soon have dandelions growing again.
The best way to get rid of these bright yellow flowers with their broad green leaves is to prevent them becoming established in your lawn in the first place. In order to do this, after each mowing, make sure you leave some grass clippings on the surface of your lawn. These will act as a mulch and will help prevent seeds from germinating. Also, make sure you do not cut your grass too short as this weakens the grass, allowing weeds like dandelions to become established. Do not allow bare patches to develop in your lawn. Make sure you rake over the bare patches, break up the soil a little and sow with new grass seeds.
However, if you continue to lose the battle against dandelions, then you could harvest them as an edible supplement for your salad bowl!