This festival is unique to Bull temple, Bangalore.
Some information about the festival which I found out from the internet is:
The legend has it that the surrounding area of the temple, known as Sunkenahalli was cultivated for groundnut. A bull started grazing in the well-grown groundnut crop, at this, a farmer got furious and hit the bull with a club. Immediately the bull sat down becoming motionless and was transformed into a stone. Poor farmers were left stun and felt guilty. For their repentance they decided to build a temple for the bull, to their surprise the bull was growing in height. The worried farmer then prayed to Lord Shiva who advised them to redeem a trident buried a few feet away from the bull and place the trident on the forehead of the stone statue to stop it from growing. Farmers followed the Lord’s advice and the bull stopped growing. Still one can see the trident place on bull’s forehead.
Since then farmers offer their first crop of groundnut to the bull. The farmer’s hold a Groundnut fair known as Kadalekayi Parishe, near the temple premises every year, to show their thankfulness. It is one of the worth visiting places in Bangalore.
I studied in B.M.S. College of Engineering which is right across the Bull temple, and I had never been to this festival.
When I reached the place, I could see lots of stalls around. Huge piles of groundnuts and people selling them.