The Diwali story of Lakshmi Puja goes like this.
It is believed that Goddess Lakshmi manifested herself on the day
when the demons and deities were churning the ocean together to find
out the 'drink of immortality', Thus Diwali festival is
celebrated to commemorate the birth of the Goddess of Wealth.
Whatever the reasons may be, however, Diwali, has always been
associated with the worshipping of Lakshmi.
"Lakshmi-Puja" on Diwali is performed to drive away the
shadows of evil spirits. . It is believed that on this day Lakshmi
walks through the green fields and loiters through the bye-lanes and
showers her blessings on man for plenty and prosperity. When the sun
sets in the evening and ceremonial worship is finished all the
homemade sweets are offered to the goddess as "NAIVEDYA"
and distributed as "PRASAD". Feasts are arranged
and gifts are exchanged on this day gaily dressed men, women and
children go to temples and fairs, visit friends and relatives. There
is a peculiar custom in Maharashtra to lightly pound dry coriander
seeds with jaggery and offer as Naivedya.
In villages cattle are adorned and worshipped by farmers as they
form the main source of their income. In south cows are offered
special veneration as they are supposed to be the incarnation of
Goddess Lakshmi and therefore they are adorned and worshipped on
this day.
Another Diwali legend reveals the story behind Lakshmi Pooja. Lakshmi Diwali Puja is celebrated by lighting deepavali lamps and Lakshmi Arati.