 Celyn

Aethnen

Afal

Afallen

Afan

Bedwen

Blodyn

Camri

Ceirios

Delia is a somewhat neglected southern charmer that stands on its own but also might be short for Adelia or Cordelia. 
 Delia's name is based on that of the Greek island of Delos, which in Greek myth was the home of Apollo and Artemis and was an epithet of the moon goddess Artemis, and later taken up by the seventeenth century pastoral poets. 
 In Britain it has been associated with the cookbook writer and broadcaster Delia Smith; in the U.S. with novelist/screenwriter Delia Ephron, who often collaborated with her sister Nora. There have been characters named Delia on Everwood and Ghost Whisperer.

Delia

Derwen

Eirin

Eirlys

This unusual (to non-Welsh speakers) is near the top of the charts in Wales, carried by the recent taste for native Welsh names. Those in Wales say it's already on the way down, but for outsiders wanting to honor their Welsh heritage, it still makes an intriguing choice.

Ffion

Ffwsia

Fioled

Gwenonwy

Gwlithlys

Helygen

Meillion

Merywen

Pren

Rhosyn

kpearl8's list "Welsh Flower Names" of 23 great name ideas:  Celyn - Rhosyn!

Welsh Flower Names

For more, use these links:
http://nookofnames.com/2012/02/20/welsh-flower-names-part-1/
 
http://nookofnames.com/2012/02/27/welsh-flower-names-part-2/