On a half-moon night in the month of Bhadra, Vrishabhanu Maharaja went to the bank of the river Yamuna at around noon to take a midday bath. At that moment he saw a huge lotus floating on the water with a golden aura as bright as a thousand suns emanating from it. When Vrishabhanu went closer to the lotus, he saw the most beautiful and radiant form of a baby girl lying within the petals of the lotus. Vishabhanu was happy to see the baby girl and took her home. His wife Kirtida was delighted when she saw the beautiful baby and immediately arranged for all kinds of religious rites to be performed and donated thousands of cows to the Brahmanas. He and his wife named the baby girl Radha.
http://internalinformation.blogspot.com
https://www.google.com/search?q=radha+yamuna