Flowers that grow best in full sun need to be able to take the heat and the direct sunlight without withering or dying. Flowering full-sun plants are called "full-sun flowers" due to living in these conditions without death or disease. Choices for these sunny flowers include many from the aster/daisy family plus others you may not expect.
Helianthus angustifolius, the narrow-leaved sunflower, is from the aster/daisy family of plants. It is a wetland perennial that attracts butterflies to the area. It will get 6 feet tall with 1/2 inch wide leaves that are 3 to 6 inches long. Flowers are yellow, 2 to 3 inches wide, and come in the summer and fall seasons. Grow narrow-leaved sunflower in moist soils in full sun. Propagate via spring or fall by root mass division, or spring by seed.
Antirrhinum majus, the common snapdragon, is from the figwort family. It is a fast-growing, easy-to-grow, hummingbird-attracting plant. Sizes will vary according to cultivars between 4 inches and 3 feet tall. It comes in a wide variety of colors. Grow common snapdragon in well-drained soil in full sun with frequent watering. Propagate via seed. It may self-sow in the right conditions.
Gerbera jamesonii, the Gerber daisy, is from the aster/daisy family. It is an easy-to-grow perennial that is great for cut flower gardens, indoor use or containers. Flowers are varied in size and in color. Ray flowers are daisy-like and between 2 1/2 to 4 inches wide. Leaves are 8 to 10 inches long and coarse. Grow a Gerber daisy in well-drained soil that is sandy or loamy. Light should be full sun but it does have a shade tolerance if light. Propagate via seed or clump division.
Crinum x powellii, the cape lily, is from the amaryllis family. It is an evergreen perennial that is easy to grow. Leaves are 3 to 4 inches long and strap-like. Flowers are in summer and fall, funnel-shaped, and 4 inches wide. Grow a cape lily in rich, moist soil in full sun or partial shade. Propagate via fall division every 3 to 5 years.
Lonicera sempervirens, the coral honeysuckle, is from the honeysuckle family. It is an easy-to-grow vine that attracts songbirds, butterflies and hummingbirds. Leaves are 1 to 3 inches long and smooth. Tubular flowers are 2 inches long and are red or orange. Fruits are orange-red berries. Grow coral honeysuckle in full sun or in partial sun. Propagate via seed. It is also drought tolerant.