As a follower of Celtic Paganism, or just paganism with Celtic elements, these deities are great to incorporate into your spells and worship.
Cernunnos
Cernunnos is the Horned God, protector of animals and instinctual behavious. He is at once linked to sexual delight, abundance and abandon as well as hunting and culling, and purifying and sacrificing. The Druids encouraged the worship of Cernunnos, attempting to replace the plethora of local deities and spirits with a national religion.
Cerridwen or Brighid
An important figure in Celtic Paganism, Cerridwen is the Maiden, and a corn (and therefore abundance and harvest) Goddess, who had a magical cauldron. the Cauldron is a feminine symbol, being linked to creation of spells and of course food. Corn goddess. As the poem above shows, she was the Mother of Taliesen, greatest and wisest of all the bards, and therefore a patron of poets and bards, and protectress of the healers and smiths. She is also connected with wolves, and some claim her cult dates to the neolithic era. Her festival Imbolc is at the 1st of February. Here's a great lens about Brighid
Danu or Dana
An Irish Mother figure Goddess of the Tuatha De Danann or the mother of 'the peoples of the goddess Danu'. She is also part of of a triad of war goddesses known collectively as the Morrigan. Danu is connected with the moon goddess Aine of Knockaine, who protects crops and cattle. Under a variety of names, including Anu and Don, Danu was worshipped through pre-Christian Europe and the Middle East.
Free eBooks (Can Be Downloaded):
Kathryn Rountree - Embracing The Witch And The GoddessFranceska De Grandis - Be A Goddess
Aleister Crowley - Absinthe The Green Goddess
Phil Hine - Devotions And Demonesses
Michael Jordan - Dictionary Of Gods And Goddesses