White mulberries are one of many species of mulberries, one whose fruit remains white when ripe. White mulberries are sweet, with a mild flavor. The dried variety can be reconstituted in water. They are a source of vitamin C and iron.
Dried mulberries can be reconstituted in water, and can also be used in herbal teas or granolas to add a bit of sweet. It is considered an invasive species in North America. If you want to dry your own mulberries, check out this tutorial.