Like her or not, Alexa Chung is part of the fashion world in a big way. The former model (now adding design to her resume for her recent collaboration with Madewell) is known for her iconic, stylish ensembles. The big names in fashion may have clever little ways to describe Alexa, but I like to think of her as queen of the peter pan collar. I feel that her regular use of it is what has helped escalate the trend in its popularity. She has taken something (in my opinion) that is associated with nerdy school-girl uniforms and has transformed it into something stylish.
I picked two dresses (see above) that I can see the style icon in. They probably won't fit everyone's taste so if you are turning your nose up, then check out this post I did on peter pan collars a few weeks ago before you give up completely on the trend.
If you like the outfit that she is wearing in the picture above, then I found a few sources here, here, and here to help get her look. Amazon.com is also a great source for inexpensive peter pan collar shirts if you just want something to go under a sweater.