Unknown Pink Flower

This plant grows about two feet tall, with a long root somewhat like a parsnip, and long thin leaves; the flowers close up at night. They self-seed and come up all over the place. Anybody know what it is?

A long busy wonderful day, starting with two loads of laundry hung out in the sun to dry, and ending with our ukulele orchestra performance of These Are a Few Of My Favorite Things. (For those of you who are curious, there will eventually be a link to The Video.) In between I weeded and trimmed and reveled in simply being outside and warm and happy with all the flowers and colors and spring smells.