“The Bon Dammes’ themes are rest, pleasure, fairies, playfulness and youthfulness. Their symbols are any fairy plants (foxglove, primrose, oak, thorn, ash). The Bon Dammes are devic Goddesses in Brittany that appear much like fairies and often act with much impishness. Having a kindly nature, the Bon Dammes inspire playful, youthful outlooks to take with us into early fall with childlike wonder in our hearts.
Follow the custom of all regions the United Kingdom (except Scotland) and take the day off. Enjoy family outings and a little leisure before the warm weather really starts to fade. Sleep in a bit, ask for a few hours off from work, get outside and play with the Bon Dammes. Leave them gifts of sparkling stones, honey, and sweet bread beneath any flower or tree that captures your eye and makes you smile. In return, the Bon Dammes will make sure your day is filled with pleasurable surprises.
Think about an activity you really enjoyed as a kid and recapture that moment sometime today. Jump down a hopscotch board, play tag with the wind, climb a tree (carefully please), pick buttercups, go berry picking, skinny-dip in a stream, or do whatever re-inspires the Bon Dammes’s youthfulness in your heart. You’ll find that this moment refreshes your entire outlook and provides extra energy for the days ahead.”
(Patricia Telesco, “365 Goddess: a daily guide to the magic and inspiration of the goddess”.)
Man, striking out here! I couldn’t find anything on Saki-yama-hime, Braciaca turned out to be a god, and I could not find anything on the Bon Dammes! I did however run across two references to “Dames”: Dames Blanches (White Ladies) and Dames Vertes (Green Ladies). Now, according to Sacred-texts.com, “the Fairy-lore of the North of France, at least of Normandy, is, as was to be expected, similar to that of the other portions of the Gotho-German race. We meet it in the fées or fairies, and the lutins or gobelins, which answer to the Kobolds, Nisses, and such like of those nations.
The Fees are small and handsome in person; they are fond of dancing in the night-time, and in their dances which are circular they form the Cercles des Fées, or fairy-rings. If any one approaches their dance, he is irresistibly impelled to take part in it. He is admitted with the greatest courtesy; but as the whirling movement increases, and goes faster and faster, his head becomes giddy, and he falls to the ground utterly exhausted. Sometimes the fées amuse themselves by flinging him up to a great height in the air, and, if not killed by the fall, he is found next morning full of bruises. These little beings, it is also said, haunt solitary springs, where they wash their linen, which they then dry by way of preference on the Druidic stones, if at hand, and lay up in the hollows of rocks or barrows, thence named Chambres or Grottes des Fées. But, further, it is said of them, like the Lutins, they select particular farms to which they resort at night, and there making use of horses, harness and utensils of all kinds, they employ themselves at various kinds of work, of which, however, no traces remain in the morning. They are fond of mounting and galloping the horses; their seat is on the neck, and they tie together locks of the mane to form stirrups. Their presence, however, always brings luck, the cattle thrive where they are, the utensils of which they have made use, if broken are mended and made as good as new. They are altogether most kind and obliging, and have been known to give cakes to those to whom they have taken a fancy.
The Fées of Normandy are, like others, guilty of child-changing. A countrywoman as she was one day carrying her child on her arm met a Fée similarly engaged, who proposed an exchange. But she would not consent, even though, she said, the Fée’s babe were nine times finer than her own. A few days after, having left her child in the house when she went to work in the fields, it appeared to her on her return that it had been changed. She immediately consulted a neighbour, who to put the matter to the proof, broke a dozen eggs and ranged the shells before the child, who instantly began to cry out, Oh! what a number of cream-pots! Oh! what a number of cream-pots! The matter was now beyond doubt, and the neighbour next advised to make it cry lustily in order to bring its real mother to it. This also succeeded; the Fee came imploring them to spare her child, and the real one should be restored.
There is another kind of Fées known in Normandy by the name of Dames Blanches, or White Ladies, who are of a less benevolent character. These lurk in narrow places, such as ravines, fords and bridges, where passengers cannot well avoid them, and there seek to attract their attention. The Dame Blanche sometimes requires him whom she thus meets to join her in a dance, or to hand her over a plank. If he does so she makes him many courtesies, and then vanishes. One of these ladies named La Dame d’ Aprigny, used to appear in a winding narrow ravine which occupied the place of the present Rue Saint Quentin at Bayeux, where, by her involved dances, she prevented any one from passing. She meantime held out her hand, inviting him to join her, and if he did so she dismissed him after a round or two; but if he drew back, she seized him and flung him into one of the ditches which were full of briars and thorns. Another Dame Blanche took her station on a narrow wooden bridge over the Dive, in the district of Falaise, named the Pont d’ Angot. She sat on it and would not allow any one to pass unless he went on his knees to her; if he refused, the Fee gave him over to the lutins, the cats, owls, and other beings which, under her sway, haunt the place, by whom he was cruelly tormented.” 
Then, there are the Dames Vertes. Patricia Monaghan writes, “The ‘Green Ladies’ of Celtic French folklore were seductive but cruel, luring travelers from the forest paths and holding them upside down over waterfalls, laughing all the while. As wind spirits, they traveled speedily over their chosen countryside, invigorating all the plant life they touched. When visible in human form, the Dames Vertes were said to be tall and seductive, dressed in long green robes, passing so lightly over the grass that it seemed only wind had disturbed it” (p. 96).
Based on this description, the Dames Vertes almost sound similar to the Rousalii or Rusalki of Russian folklore who were also reported to have worn green robes…curious, very curious indeed…
In conclusion, it would seem to me that Bon Dammes would translate to “Good Ladies” and either be related to the Dames Blanches or actually be the Dames Blanches as they clearly don’t fit the description of the Dames Vertes.
Monaghan, Patricia. The New Book of Goddess and Heroines, “Dames Vertes”.
Sacred-texts.com, “The Fairy Mythology: Celts and Cymry: France“.
Cymru, Gordd. Celtic-twilight.com, “The Fairy Mythology – Great Britain“.
O’Keeffe, Christine. Tartanplace.com, “Christine’s Faery List: Dames Vertes“.
Phillips, Valerie. Dnaalchemy.com, “Devas, Elementals and Fairies“.