I had fun last year designing and assisting with the installation of an all-native, waterside buffer garden at Lake Hayward, East Haddam, CT. Now the garden is maturing and we saw yarrow and penstemon (aka beardstongue) in full bloom on June 21, 2014. Both plants have a lot of ecological value. Penstemon is recognized by the Xerces Society as attracting large numbers of native bees. Yarrow is both attractive to native bees and also attracts predatory or parasitoid insects that prey upon pest insects.
See the Lake Hayward garden web site.