There is no flower better at attracting birds than the Sunflower. The primary reason: sunflower seeds, which are the preferred seed of many species of birds, including: Northern Cardinal, Black-Capped Chickadee, and Rose-Breasted Grosbeak (among many more). Sunflowers will also attract insects, which in turn attract insectivorous birds. Birds will even use parts of the Sunflower stalk when they build their nests. Also note that the Ruby-Throated Hummingbird will occasionally extract nectar from sunflowers. For full profile see: Attracting Birds with Sunflower.
Many regard Goldenrod as a weed, birds do not - it attracts lots of insects and produces lots of seeds. The high nectar content of Goldenrod brings in heaps of bees, wasps, and other flying insects - which in turn attract insectivorous birds like the Eastern Phoebe and Warblers. The seeds of Goldenrod a favorite of: Indigo Bunting and Dark-Eyed Junco. For full profile see: Attracting Birds with Goldenrod.
3. Virginia Creeper
A vine, Virginia Creeper primarily grows up trees. In late summer/early fall the vine will being to produce berries, once mature these berries will attract all different sorts of birds - from Pileated Woodpecker to Scarlet Tanager. For full profile see: Attracting Birds with Virginia Creeper.
4. Wild Blackberry
Growing Wild Blackberry is a fantastic option for anyone looking to attract birds. In spring Wild Blackberry produces small, nectar-filled flowers which attract flying insects, the insects attract birds like the Baltimore Oriole. In summer, the flowers give way to blackberries, which many birds eat. Wild Blackberry thickets will provide shelter for birds year-round, especially for birds that prefer to nest and forage in thickened areas, like: Indigo Bunting, Brown Thrasher, and many species of Sparrow. For for full profile see: Attracting Birds with Wild Blackberry.
5. Trumpet Honeysuckle
A vine that blooms abundant scarlet colored, tubular-shaped flowers. The flowers are a favorite nectar source for the Ruby-Throated Hummingbird, in fact growing Trumpet Honeysuckle greatly increases your odds of attracting them. In late summer, early fall the flowers give way to small red berries, which are eaten by numerous species of bird, among them: Cedar Waxwing and Baltimore Oriole. For full profile see: Attracting Birds with Trumpet Honeysuckle.
6. New England Aster
In late summer/early fall both insects and birds become more desperate for food - nectar sources become rarer for insects, which means insects becomes rarer for birds - New England Aster is a solution to this problem. New England Aster is a nectar rich flower that blooms in late summer/early fall and thus becomes a hot spot for insects, which later become food for insectivorous birds. The seed heads of New England Aster are eaten by birds like the American Goldfinch later into the fall and winter. For full profile see: Attracting Birds with New England Aster.
7. American Boneset
A long bloom season ( July to September) and very high nectar content make Boneset a great option for attracting insects, which in turn attract insectivorous birds, like Warblers. For full profile see: Attracting Birds with American Boneset.
A rigorous vine, Pokeweed blooms small white flowers in summer, that give way to abundant purple berries in late summer/early fall. The berries attract many birds, among them: American Robin, Hermit Thrush, and Eastern Bluebird. For full profile see: Attracting Birds with Pokeweed.
9. Purple Coneflower
This garden-favorite blooms in summer and is quite attractive to insects and butterflies. The insects in turn attract insectivorous birds. The seed head of Purple Coneflower draws in American Goldfinch and Black-Capped-Chickadee. For full profile see: Attracting Birds with Purple Coneflower.
10. Cardinal Flower
A hummingbird favorite, Cardinal Flower blooms in mid-summer. Its nectar will also attract insects, which will in turn attract insectivorous birds. For full profile see: Attracting Birds with Cardinal Flower.