When you crush the leaves they give off a wonderful scent reminiscent of pineapple. It is a relative of chamomile, and you can make a tea from it. When I did this, however, the tea was disappointingly bland. It is undaunted by dogs, lawnmowers, and chemicals alike. This is an argument not to sample this edible plant.
Pineapple weed emerges in the spring and lasts into the fall.