Rukmaganda, the son of King Bhima of Koudinyapur, was on a hunting trip when he stopped at the hermitage of Rishi Vachaknavi. The rishi’s wife, Mukunda, fell in love with him, but Rukmaganda refused her and left. She became lovesick. 
Indra then came to her in the form of Rukmaganda and left her pregnant. She had a son, Gritsamada. Eventually, he learned of his birth and cursed his mother to become an unattractive, thorny, berry-bearing bhor plant. Mukunda also cursed Gritsamada that a demon would be born from him. Suddenly they both heard a heavenly voice saying, "Gritsamada is the son of Indra", leaving them both shocked, but too late to alter their respective curses. 
Mukunda was transformed into the bhor plant and Gritsamada, ashamed and penitent, retreated to the Pushpak forest, where he prayed to Ganesh. Ganesh blessed Gritsamada that he would have a son undefeated by all but Shiva. Gritsamada also asked Ganesh to bless the forest and stay there. 
The idol installed here is called Varadavinayaka. It is believed that if one consumes a coconut received from here as prasad during Mag Chaturthi, one will be blessed with a child.