Sunflower

Multiple uses for sunflowers exist: food, fuel, fiber.

(Text was in part excerpted from corresponding Appropedia page: "sunflower")

The sunflower (Helianthus annuus) is an annual plant with large flowers. It is an important food crop worldwide and is native to North America.

Uses

food: The raw sunflower kernels can be eaten raw, or used in baking or cooking. They are also excellent feed for birds and wildlife, and can be stockpiled to feed birds in your own garden during the colder months.
cut flower for the floral industry.
The stems can be turned into paper.
sunflower oil from pressed seeds
the oil can be turned into biodiesel
see Jerusalem Artichoke, which is a type of sunflower

Sunflowers are a good garden plant and they're a great flower for children to grow when learning about gardening.
Soil: Sunflowers can tolerate both light and heavy soil, provided it drains well. However, the sunflower will grow best when the soil has plenty of organic matter and some fertiliser.
Sow seed in late spring or early summer, as long as the soil is warm. Be generous with the seeds, as you can thin out the seedlings once they take. Place 1cm/ .5 inches of soil over the top of the seed once planted. If the seed is really large, cover with 2.5cm or 1 inch of soil.
Expect germination in about five to ten days. Keep the soil moist. Thin out the seedlings for best growth and large flowers. If the flowers are kept spaced close together, they form smaller and shorter flowers.

Water during dry weather.
Remove weeds to prevent the weeds competing with the sunflower plant.
If you remove spent flowers, the flowering will be prolonged, as is typical with many annuals.
Other than these basic care methods, sunflowers don't require much intervention while growing.