Nasturtium: It's at the top of my list because it's ornamental, useful, easy to grow and has a lovely variety to choose from. The seeds are quite large, so they are perfect for children to plant. They need a sunny location but can take just about any soil. Nasturtium is known as being drought tolerant but I've found over the years it does much better if watered on a regular basis. The seeds germinate in about 12 days from sowing, and is very dependable. I've planted a lot of the varieties out there but these are my favorites:
Alaska: The foliage is almost as pretty as the blooms. It's green and a creamy white mixed in splotches with the flowers usually shades of orange and yellow.
Cherry: This variety grows a bit smaller than the others with a pretty muted red bloom that has a light, lovely fragrance. The bloom is the same size as the others, but the plant itself sprawls less than the other varieties.
Moonlight: A creamy yellow nasturtium that grows big and full with a lot of blooms. The soft yellow is lovely in window boxes, raised beds, containers or planted around the garden in the corners.
Empress of India: A deep red nasturtium with a medium sprawl that works great as a border plant in a flower bed or a vegetable garden.
Calendula: In the past it was known as "pot marigold" and didn't really find the popularity it's cousin, French marigold, did as an annual flower. It was known more as an edible flower and herb because the petals of the blooms can be used in salads, soups and other dishes much like saffron. It germinates in about a week, and grows fairly quickly. If the flowers are kept deadheaded it will continue to bloom until a heavy frost in the fall. I prefer calendula over marigolds, and already have some coming up from seeds dropped last season.
Touch of Red: A mix of yellows, oranges and a blending of cream and red with dark centers.
Bon Bon Calendula: A dwarf mixture of oranges and yellows in different shades.
Flashback: This is a neat variety that offers softer and brighter colors with some double blooms. It's an especially nice mix.
Basil: It can be a bit tricky to grow inside and transplant but if you wait until the temperatures are above 50 degrees F. at night, it's fairly easy to sow. The only thing to remember about Basil is if you want to keep it going until fall, it's important to pinch off the buds if it starts to form flowers. The leaves are the culinary treasure, and flowering will stop production. The seeds are very tiny, so sow carefully, cover lightly with soil and water gently. The following are good varieties to grow.
Sweet basil: The standard basil which is still the best overall variety and always easy to find.
Lemon basil: A lovely lemon scented basil.
Cinnamon basil: I different scent and flavor to try.
Globe Basil: this one has a very compact shape more like a small bush. Works well for containers or small spaces.
Large Leaf Basil: If pesto is your goal, then this is a perfect variety because the leaves grow large and are easy to handle.
On OFL we have an article with more basil tips and recipes: