Stevia (Stevia rebaudiana) is native to Central and South America. And you can grow it in your garden, too! It is a natural sweetener, minus the many negatives that sugar conveys. It is approximately 200x as sweet as sugar, but can have a bitter aftertaste. Studies with stevia have shown it to be helpful in balancing glucose levels, reducing LDL cholesterol and as an anti-inflammatory.
Stevia plants are becoming more available at local nurseries or you can buy seeds and cultivate it yourself. This winter, I moved my plants inside and they survived. I cut back the stems and they are blooming again. You can also harvest the leaves and dry them for future use. Pulverize the dried leaves in a mini food processor or coffee grinder.
If you buy commercial stevia, try to ensure that it doesn't have a lot of other ingredients. You can use the fresh or dried leaves directly in tea. Place a stevia leaf in a mug and pour boiling water into the cup along with your favorite tea. Or add some to your smoothie.
Remember it is very sweet and a little bit goes a long way.
Here's my plant with the little leaves reemerging.