Asters, daisies, sunflowers, thistles, etc. Generally each “flower” is composed of many miniscule flowers of which there may be two types, tiny “disk” flowers in the middle, and larger “ray” flowers (that often look like normal petals) on the outside. (Some plants have only ray flowers, others only disk, some both types, some have separate male/female flowers where one or the other may not be either ray or disk).
In this coastal tarweed flower you can actually see how the disk flowers are real flowers with five petals. The ray flowers only seem to have one petal (or perhaps several petals fused into one). The branched style is clearly visible at the base of the ray flower, while the fused anthers (in dark purple) are obvious in the middle of the disk flower.