108 lotus flowers are offered to Goddess Durga during Durga Puja. The ritual is strictly followed especially during Sandhi Puja. There is a famous story associated with this important flower offering.
There are two stories in Hindu Bengali tradition behind offering
108 lotuses.
The Tale of the 108 Wounds:
During the slaying of the demons, 108 wounds were created
all over the Goddess's body. To alleviate the pain of these wounds, Lord Shiva
advised Goddess Durga to bathe in Devidah (the divine pond). After bathing in
Devidah, 107 lotuses were created from 107 of her wounds. Seeing the Goddess
suffering from the pain of her wounds, a tear fell from Mahadev's eye. This
tear drop fell on the Goddess's 108th wound. This last remaining wound also
vanished. The 107 lotuses, however, remained in Devidah.
Rama's Offering in the Treta Yuga:
In the Treta Yuga, seeking to slay Ravana, Lord Rama wished to offer 108 lotuses to Goddess Durga at the end of the Sandhi Puja. He sent Hanuman to Devidah. However, as there were only 107 lotuses in Devidah, Hanuman returned with only 107. As the junction period for offering lotuses at the Mother's feet was about to pass, Lord Rama was prepared to pluck out one of his own eyes, which resembled a blue lotus, and offer it as the 108th lotus. At this moment, the Goddess appeared. Strengthened by the Mother's blessing, Lord Rama slayed Ravana during this very junction period.