What do periwinkles look like?
What Do Perwinkles Look Like?
Certified GKH Gardening Expert
If you are referring to perwinkle (Vinca), this article will help: https://www.gardeningknowhow.com/ornamental/groundcover/periwinkle/growing-periwinkle.htm
There are many varieties of periwinkle. They are a beautiful rounded blue flower that resembles the daisy - some are full with double petals (which look like a double daisey) and others are five petal flowers. There are some good pictures on google. They are often used at weddings. Hope this helps.