Carolina Bush Pea (Thermopsis villosa) is a perennial that is native to mountain balds in the Southeast. It grows just as happily in the piedmont and coastal plain as it does in the mountains and is quite a large plant, with flower spires that often reach 5' in height. I have heard complaints from other gardeners that the flowers don't last very long but that has not been the case in my garden; the flower spires (including the bud phase) usually last at least 3 weeks. The color is a clear buttery yellow that goes with everything.
Carolina Bush Pea beginning to open up with a late very fragrant yellow iris (Harvest of Memories), foxglove, and Verbena bonariensis. All of the green spires in the picture are Carolina Bush Pea.
Carolina Bush Pea with spiderworts, Hubricht's Blue Star, and Rosa rugosa alba.
View across big perennial bed toward neighbor's pasture.