Natural antidepressants are part of alternative or traditional medicines. To treat mild depression, there are some "natural remedies" like psychotherapy, natural antidepressant, homeopathy, acupuncture, luminotherapy or a diet rich in omega -3.
Here a list of some natural antidepressants (herbs and food)
Turmeric (read article Turmeric, is a more effective antidepressant than prozac)
St. John’s Wort
Nuts: rich in omega 3
Fruits: kiwis, oranges, strawberries, clementines, grapefruits, lemons, chestnuts are among the fruits richest in vitamin C
Source : https://www.magazinescience.com/en/health/natural-antidepressants/