In this shot you can see the shiny bracts that cover the unopened buds in the center of nodding beggar-ticks flower heads. This image doesn't really do them justice. They can be even shinier and more golden, giving an effect very much like a jewel surrounded by opened flowers.
Many species of beggar-ticks have heads with only the small center flowers. But those species will occasionally have some ray flowers. Those rays may be few, small and irregular. In contrast, nodding beggar-ticks typically has regularly-spaced large and showy rays. But the heads may sometimes not have the rays, showing us only the small center flowers.