Formal:
* Gyda chariad oddi wrth... (This is the most literal and formal translation)
Informal:
* Yn garedig iawn oddi wrth... (This is a more natural and less formal translation, meaning "With much love from...")
* Caru chi oddi wrth... (This means "Love you from..." and is a very informal and affectionate option)
You can replace the "..." with the name of the person sending the message.
For example:
* Gyda chariad oddi wrth Megan (With love from Megan)
* Yn garedig iawn oddi wrth Dafydd (With much love from Dafydd)
* Caru chi oddi wrth Nia (Love you from Nia)