There are quite a few different species of native penstemons, commonly called beardtongues. These are relatives of some non-native familiar cultivated plants, like snapdragons and foxgloves. This one, which is also sometimes called tall white beardtongue, is a carefree, lovely plant with lots of white flowers. 

While we have planted plugs of this plant in some areas, this one must have come up from seed in one of the seed mixes we scattered when we stopped mowing this area. Hopefully it will spread a lot! These bloom for a long time and the flowers are attractive to a variety of bees and sometimes even hummingbirds. If you plant this in your flowerbed, it is likely that seedlings of it will come up in other places. While some gardeners might not like this, it should be very easy to weed out if it comes up where it's not wanted. You can see how these spread in the more formal gardens on the trail, including the one by the cafe at Cynwyd Station.