Jai MAA! And a blessed Ambubachi to all of you. Ambubachi is the festival of the menstruation of Mother Earth, and is celebrated at the Sri Sri Kamakhya Temple in Assam, where the Goddess Kamakhya is venerated as the yoni (which means source, vulva, or womb) of the Mother Goddess. Kamakhya is closely associated with Kali and Chandi (Durga), as well as the Mahavidyas, the ten fierce wisdom Goddesses of the Tantric tradition.
Ambubachi began on Monday, and continues through Thursday.
I've published a couple of articles on this festival, as well as ways to celebrate it in your own home here: