Two tall yellow flowers, a Rudbeckia, and a Helenium(?)
The Rudbeckia maxima, the giant coneflower is blooming now. The plant has a rosette of silver green leaves that are probably not more than a foot tall but it sends up a flower spike over 6 feet tall. Some say it can attain a height of 8 feet!. The flower itself is not very large, not any bigger than Echinacea but the Goldfinches really love the dark brown almost black seedhead. They prefer it over the Echinacea seedhead which they also eat.
I thought this was a Rudbeckia but it doesn't form a cone so it may be a Helenium instead? The leaves sure look like cone flower leaves so it may still be some kind of Rudbeckia. I don't know where this plant came from but it appears that we bought it when it may have been fairly small in the pot. I has grown to about 5 feet tall and though in full sun the stalks have fallen somewhat making it a sprawling and untidy plant. I was threatening to dig it up but decided to keep it until past bloom but the flowers are very long lived - it's been blooming for at least 3 weeks with out showing any signs of fading. The color of the flower turns from bright yellow to a yellow orange as it ages.
Thanks to Annie in Austin, the Helenium? has been identified as Heliopsis scabra 'Summer Sun'. Here's an image from the Bluestone Perennials website.