“Bai Mundan’s themes are love, devotion, romance, femininity and promises. Her symbols are any items associated with love and romance; and the peony. This Goddess is beautiful and sensual, but also filled with only the most honorable intentions. It is Her sacred task to tempt the ascetics in the keeping of their vows (turning the tables somehow on the theme of this holiday). Her name means ‘white peony’, a flower that in Chinese tradition affords this Goddess’s protection.
The story of Ch’un Hyang is one of the best known ancient novels of Korea. The heroine, Ch’un Hyang, secretly married a nobleman’s son. Even when beaten by a lusty governor, however, she remained devoted and refused all advances, as if guided by Bai Mundan’s fidelity and esteem. For modern-minded people, this basically means ‘loving the one you’re with’ and really appreciating their companionship today. If it’s been a while since you’ve gotten your partner a gift for no reason, or spent quality time alone with them, by all means, do so! Bai Mundan’s energy is wherever two hearts emit true, faithful emotions.
If you don’t have a partner, try this Bai Mundan love spell. You’ll need a white peony (or any other white-petaled flower, like a daisy). Slowly tear off all the petals, saying,
‘Bai Mundan, for love I ask; help me in this sacred task.’
Let the earth and air accept the petals but one, which you should carry with you as a love charm. Release it in thankfulness when your wish is answered.”
(Patricia Telesco, “365 Goddess: a daily guide to the magic and inspiration of the goddess”.)
It took me quite awhile to pan out anything Goddess related for Bai Mundan. At first, I found that Bai Mudan or Bai Mu Dan, is known as ‘White Peony’ and is a type of White tea made from plucks, each with one leaf shoot and two immediate young leaves. 
I also found that Bai Mu Dan was a character in a Singapore TV series entitled “Legend of the Eight Immortals“; though Bai Mu Dan wasn’t a part of the original Eight Immortals of Chinese mythology (or so I originally thought) as Immortal Woman He, or He Xiangu, was the only female deity among them…
I found some clips on Youtube of a Chinese opera called “Lu Dongbin and Bai Mudan“. Lu Dongbin, or Lǚ Dòngbīn, is a historical figure and also a deity/Immortal revered by many in the Chinese culture sphere, especially by Daoists/Taoists. Lǚ Dòngbīn is one of the most widely known of the group of deities known as the Eight Immortals and considered by some to be the de facto leader. 
Lǚ Dòngbīn’s apparent well known overindulgence and taste for women led me to a story in which Lǚ Dòngbīn once incurred the wrath of a heavenly queen for wooing the famous Luoyang courtesan White Peony.  On the Foundations of Daoist Ritual, 6 – 8, it sites a few more references to White Peony: from the book “The Taoist Body” by Kristofer Schipper, it describes Lü Tung-Pin’s (Lǚ Dòngbīn) seduction of White Peony, or Ho Hsien-ku (the Immortal Maiden Ho) as the future Immortal would be called. After making love with Lü Tung-Pin, She received his “powerful drug of immortality [and] in this way it happened that the young woman was victorious in the battle of love and, at the same time, fulfilled Lü’s desire by allowing him to recruit the Immortal he needed to complete his band” to bring to the Queen Mother of the West‘s forthcoming banquet of peaches.  So, I do conclude that Bai Mundan (White Peony) is indeed Ho Hsien-ku.
A reference to White Peony is also made in the Ming-dynasty novel Pure Yang Lu: of the Tang Dynasty Achieves the Dao, the 5th chapter “Pure Yang Lu: Sleeps with White Peony”, based on the play Lu: Dongbin’s love affair with White Peony, “Yellow Dragon is the instigator.” 
Foundations of Daoist Ritual, 6 – 8, “White Peony“.
Schipper, Kristofer Marinus. The Taoist Body, “The Immortals” (p. 163).
Taiwan-panorama.com, “It’s a God’s Life“.
Wikipedia, “Bai Mudan Tea“.
Wikipedia, “Lü Dongbin“.