The leaves are edible, but it is not traditionally grown for the sole purpose of consumption and therefore did not undergo certification.

Calendula, marigold, is a genus of about 12–20 species of annual or perennial herbaceous plants in the daisy family Asteraceae, native to an area from Macaronesia east through the Mediterranean to Iran. Calendula should not be confused with other plants that are also known as marigolds, such as corn marigold, desert marigold, marsh marigold, or plants of the genus Tagetes.

The most commonly cultivated and used member of the genus is the pot marigold (Calendula officinalis). Herbal and cosmetic products named 'calendula' invariably derive from C. officinalis.

Plant pharmacological studies have suggested that Calendula extracts have anti-viral, anti-genotoxic, and anti-inflammatory properties in vitro^.  In herbalism, Calendula in suspension or in tincture is used topically for acne, reducing inflammation, controlling bleeding, and soothing irritated tissue. There is limited evidence that Calendula cream or ointment is effective in treating radiation dermatitis.  In a randomized study of 254 radiation patients, topical application of 4% calendula ointment resulted in far fewer occurrences of Grade 2 or higher dermatitis than occurred in the group using trolamine. Calendula users also experienced less radiation-induced pain and fewer breaks in treatment.

Source: Wikipedia