The main legend is from Mahabharata.
When Pandavas were in exile, Lord Krishna gave Draupadi a bowl called the Akshaya Pathram.
The word Akshaya means that which never diminishes and this bowl is said to have given infinite food to the Pandavas.
This is why this day is considered to be a good time to bring home Goddess Lakshmi, in any form, gold, silver or platinum. Valuables that are acquired on this day are said to be replenished endlessly.
There is also another legend associated with the day, also known as Akha Teej, in North India.
This is celebrated as the birthday of Parshurama, the sixth incarnation of Vishnu marking the beginning of Golden Age. Parshuram is the son of Jamadagni and Renuka.
One day, when Jamadagni got angry with his wife Renuka, he commanded Parshuram to kill her.
Obeying his father's command, he killed his mother. In return, when Jamadagni offered his son a boon, he got his mother back to life.
Associated with the Mahabarata, is another story behind the origin of the day.
It was on this day that the Pandavas unearthed weapons that clinched them their victory over the Kauravas.
It is also believed that Goddess Vijaya Chamundeshwari killed an Asura on this day.
It was also on this day that Ved Vyasa, along with Lord Ganesha, is believed to have started writing the Mahabharata.
And according to the puranas, this day marks the beginning of the Treta Yuga, which is the second out of four yugas, or ages of man, in Hindu religion, following the Satya Yuga of perfect morality and preceding the Dvapara Yuga.
The most famous events in this yuga were Lord Vishnu's fifth, sixth and seventh incarnations as Vamana, Parasurama and Ramachandra respectively.