I'm going to be honest, I'm not much of a fan of the sport but I will most definitely take the stripes.
J. Crew Vintage cotton rugby-stripe henley $29.99 (sale)
I picked up the white and red shirts (also available in chalk) on sale over the weekend from J. Crew. They are available online but slightly lower in price in store.
I hope someday that I will have a small dog that will love stripes too. Good to know I can outfit my future pup in Ralph Lauren.