Dandelions can be a real nuisance in the garden. They pop up everywhere and can be a real pain to get rid of - if you are digging them out they will keep on coming back again and again unless you remove every single bit of their root. Even though they can be a pain it's really worthwhile to try and find a corner for them to grow in during Spring. Dandelion blooms mark the start of the honey bee season and provide an invaluable source of food for them when there is little else for them to feed on.
It is best to get rid of them before they go to seed though, and spread themselves all over your plot. The seed heads may be very beautiful, but they do do a very effective job at continuing their species sending seeds all over the place with each gust of wind!