Catananche caerulea or Cupid's Dart has narrow leaves radiating from a root crown making this part of the plant similar to a dandelion - but the flowerhead, held on a long thin stalk is quite different.
The petals are broad and flat, usually rich lavender/blue and have serrated edges - making them look a little like cornflowers. There are also white cultivars available.
These are very cottage garden type flowers and also go very well in amongst grasses.
Catananche caerulea is a rather short lived perennial and is excellent for dried flower arrangements.