The Pandavas
As per the great epic Mahabharata, the Pandavas after wandering in the forest for 12 years, hung their weapons on a Shami tree before entering the court of king Virata to spend the last one year in disguise. After the completion of that year on Vijayadashmi the day of Dassera they brought down the weapons from the Shami tree and declared their true identity. Since that day the exchange of Shami leaves on Dassera day became symbol of goodwill and victory.

Kautsa
Kautsa, the young son of Devdatt, insisted on his guru Varatantu to accept "gurudakshina", after finishing his education. After lots of persistence his Guru, finally asked for 14 crore gold coins, one crore for each of the 14 sciences he taught Kautsa. Kautsa went to king Raghuraj, who was known for his genorisity and was an ancestor of Rama. But just at that time he had emptied all his coffers on the Brahmins, after performing the Vishvajit sacrifice. So, the king went to Lord Indra and asked for the gold coins. Indra summoned Kuber, the god of wealth. Indra told Kuber, "Make a rain of gold coins fall on the "shanu" and "apati" trees round Raghuraja's city of Ayodhya." The rain of coins began to fall. The king Raghu gave all the coins to Kautsa, who gave 14 crores gold coins to his guru. The remaining coins were lavishly distributed to the people of Ayodhya city. This happened on the day of Dussehra. In remembrance of this event the custom is kept as collecting the leaves of the "apati" trees and people present each other these leaves as "sone" (gold).