Isis is one of the oldest members of this group of mother goddesses, but she only has one child. Some of these ladies have far more. It's a great group for baby gods to hang out and play together.
As a planetary goddess of the Greeks, Gaia is not just a mother, she is the Mother—Mother Earth, to be precise. Gaia has more kids and grandkids and great grandkids than Isis can shake her sistrum at. Her entire purpose is to be mothering, which makes her the obvious president of the Big Mamas.
Even her name says Mama! Pachamama, "mother of the land," joins the Big Mamas as the mother goddess of the Inka and other neighboring peoples in South America. She's big and beautiful, loves planting flowers, and people still toast to her honor before drinking. Don't make her angry, or you might end up with an earthquake!