I think of rudbeckia, alias black-eyed susans, as one of the iconic, traditional perennials. I remember seeing their sunshine blooms before I had planted my first garden, and thinking 'I want that flower'. So of course when I started perennial gardening, I bought a few $1.99 starters of rudbeckia to plant in several spots. This makes me laugh now that I know how aggressively it can spread, and every year I pull or donate the equivalent of many, many starter size rudbeckia. But I have no regrets - I love this sunny, golden bloom as much now as when I envied it in others' gardens. The dreamy chocolate brown centers romance like big brown eyes. The simple, golden petals cheer the fading summer garden, mixing well with russian sage, cone flowers or phlox, for a classic cottage garden wave of colour. As a child, I picked the native wildflower version (brown-eyed susans) from the ditches, to bring my Mom tattered bouquets.
Technical stuff - hardy perennial to Zone 3, height of about 30", can be aggressive spreader in happy spot, likes sun to part sun and most soils, drought-tolerant, blooms mid-summer to frost, with wonderful seed heads for winter interest.