Notre-Dame d’Err, the Black Virgin, Morénéta
According to legend this ‘Black Madonna’ (as the locals still insist on calling her) was found miraculously in a tree by an animal guiding its shepherd. (For more on this theme see Olot.) This must have been some time before the year 930 when she received her own church right next to the parish church of the little village. Unusual indeed. Black Madonnas often demand their own churches, but never right next to an existing one. I suspect there was some feud between two groups that refused to worship together.
Our Lady of Err has a powerful reputation for averting all kinds of calamities. She heals humans and animals, ends droughts, and stops fires. She puts all things in order.
In 1726 the parish council decides on the 2nd of July as the feast day of the Black Madonna of Err, to be celebrated with a procession that follows the exact same path ever since. The statue is taken down from her high altar the night before to be closer to her people. She is carried in procession by four girls wearing white dresses and veils.
Ean Begg mentions "fairy grottoes" in connection with this Madonna, but I couldn't find any more information about them. ("The Cult of the Black Virgin", Arkana, 1985, p. 187)