Tacitus says that seven northern nations worship Mother Earth, who is named Nerthus . Among the tribes that he says worship Nerthus are the Longobardi (Lombards).
In the History of the Lombards by Paul the Deacon c. 750, the now Christian Lombards have a legend among them, "a silly fable told by told men" about how Odin's wife Frigg (called Godan and Frea) tricked Odin into giving them the name Longbards, and thus demanded that he also give them the victory. The trick involved Frigg telling the tribe to have their women come with them, their long hair arranged like beards, and assemble on the battlefield together. That evening, Frigg turned his bed around so that in the morning, Odin (called Godan) wakes and first sees this strange sight on the battlefield and asks, "Who are these Long-Beards?".
This explains the statement in Tacitus Germania ch. 40 that the Lombards are a small but fierce tribe who can hold their own against more powerful neighbors. The Lombard Saga naturally explains why. Odin's Wife Frigg secured victory for them and gave them a new name the Lombards (Longobards), prior to that, they were known as the Winnilli. In doing so, Odin sanctioned their women to fight alongside their men men on the battlefield.In Tacitus the Longobards worship Nerthus, and in their own history, recorded 600 years later, they say Frigg helped them acquire their name-- the same one which Tacitus uses for them.
If these two histories can be connected, then Frigg ("the beloved") is also known as Nerthus, "who is Mother Earth". Her brother is the sea, Njord. They are the parents of Freyr and Freyja. In the temple of Uppsala the idol of Freyr is called Fricco, which is a masculine version of Fricca, Frekka, Frigga, Odin's wife. In Skaldic poetry, "Odin's wife" is a kenning for the Earth, Thor's mother. Frigg is the mother of Baldur, her only child if you believe Snorri. So if Frigg is Nerthus, Mother Earth, then she is the mother of Thor and the Twins, Baldur and Hodr, by Odin; and the twins Freyr and Freyja by her own brother Njord. She is the Mother of the Gods. In the skaldic poem, the gods are said to be Frigg's progeny..In Voluspa 4, the three sons of Borr, Odin and his brothers, lift Jord (earth) up from the sea, and they all three have relations with her (Lokasenna 24). For that Loki calls her the "man-maddest of women". Solarljod 78 states that "Odin's wife rows in earth's ship, eager after pleasure." According to Snorri, Thor's mother is called Jord, Fjorgyn, Hlodyn,, and other names. Frigg's father is named Fjorgynr (a masculine version of the name of Thor's mother Fjorgyn). In Gylfaginning 10, Jord has a brother named Audr, which translates as "Wealth" and also Udr, i.e. Unnr "wave". Njord is called the "wealthy" (audigr) and he is a god of the sea. So she appears to be the same as "the Mother of the Gods" named in Germania 45, and described as a goddess of a tribe of farmers, whose emblem is a boar, a symbol closely associated with the Vanir gods, suggesting Frigg is a Van by birth. This helps explain her strength and power in Asgard. When she and Odin disagree, she always gets the better of him..In Harbardsljod 4, Thor says if his mother were dead, all men would mourn. She is Frigg, the "Beloved"; Mother of Gods and Men per the Anglo-Saxon Aecerbot Charm. Like her husband Odin, Frigg is a powerful goddess in her own right, known by a number of names.
According to Snorri Frigg has no alternate names, and plays a minor role in the myths. Snorri counts Jord among the Asynjes, but she plays no role in any known myth. In Snorri's Edda, Jord has many names, but Frigg does not. An independent study of the eddic and skaldic poems, however, makes it apparent that Frigg and Jord are alternate names of one figure, both called Odin's wife. They are not "rivals" as Snorri says. the only poetic attestation we have of the usage is Rind as "rival" of Frigg.
-William P Reeves “ Odin’s Wife, Mother Earth in Germanic Mythology