I'd never heard of this character until I saw her in The Wicca Deck (Morningstar, US Games 2014). The companion book makes no explanation, but some sources I've found say the 'Queen of Elphame' is mentioned in witchcraft trial transcripts, where she is said to be a form taken on by the Devil. She also appears in a few Scottish ballads, such as Thomas the Rhymer:
True Thomas lay oer yond grassy bank,
And he beheld a ladie gay,
A ladie that was brisk and bold,
Come riding oer the fernie brae.
True Thomas he took off his hat,
And bowed him low down till his knee:
“All hail, thou mighty Queen of Heaven!
For your peer on earth I never did see.”
“O no, O no, True Thomas,” she says,
“That name does not belong to me;
I am but the queen of fair Elfland,
And I’m come here for to visit thee.
Apparently, Elphame means Elfland. In the image, above the cave or doorway the Queen has presumably just emerged from, are the words 'Thierna na oge'. Again, the companion book makes no explanation of this. I googled it and to my surprise, I got a lot of hits from DC Comics! Apparently it is named as one of the 'five lost cities of Atlantis' in the Aquaman comics. Ha! Further searching brought up this: Fairy Legends - Thierna na Oge. According to this source, Thierna na oge is a city or palace under water, which was submerged by the water from a spring or well as a result of the king their trying to horde the water for himself. After much clicking and frowning, I found this: Tir na nOg, Land of the Young. Which makes more sense if we're talking about elves or faeries! Those who live in Tir na nOg are the Tuatha De Danaan, at last a term I've heard! These are the faery folk or deities of pre-Christian Ireland. And it looks like Queen of Elphame is their queen, at least in this card. Not that the companion book would tell you ANY of that.
Instead, it says that is the leader of the fairy and little people and is also known as Morrigan and embodies the Triple Goddess as well as Morgan le Fay and the Lady of the Lake. It's certainly Wicca to take various strands and stir them up together like that.
She's meant to be telling me today that 'magic and beauty' are touch me. 'Seek the magic in all situations and call upon the Elven Queen to guide your journey,' it says.
Well. Okay. :)