The dandelion weed is the weed that looks like a white puff ball, and you blow the buds away on the white puff ball as you make a wish. I love blowing the buds away, but my husband has a fit since it can spread the weeds all over the yard.
I agree with the other posters that you are probably referring to the dandelion.
The dandelion is considered a weed by many people but it should be known that the leaves are not only edible but very healthy! A bit on the bitter side but commonly used by fancy restaurants in salads.
I guess one person's weed is another person's treasure! ;)