“Tellus Mater’s themes are earth, ecology, promises, abundance, prosperity and fertility. Her symbols are the globe, soil and grain. The Roman Earth Mother celebrates today’s festivities, the Earth’s Birthday, by sharing of Her abundance, being a Goddess of vegetation, reproduction, and increase. In regional stories, Tellus Mater gave birth to humans, which is why bodies are returned to the soil at death – so they can be reborn from Her womb anew.
According to James Ussher, a seventeenth-century Anglican archbishop, God created the earth on October 26, 4004 B.C.E. While this date is uncertain at best, it gives us a good excuse to honor Tellus Mater and hold a birthday party on Her behalf.
Make a special cake for the Earth Mother out of natural fertilizers. Take this to a natural setting (don’t forget the candle). Light the candle and wish for the earth’s renewal, then blow it out, remove the candle, and bury your gift to Tellus Mater in the soil, where it can begin manifesting your good wishes!
While you’re outside, pick up a pinch of soil, a stone, or any natural object that strikes your eye and keep it close. This is a part of Tellus Mater, and it will maintain her power for abundance wherever you go today. It will also help you stay close to the Earth Mother and honor the living spirit of earth in word and deed.”
(Patricia Telesco, “365 Goddess: a daily guide to the magic and inspiration of the goddess”.)
“In ancient Roman religion and myth, Tellus or Terra Mater (‘Mother Earth’) is a Goddess of the earth. Although Tellus and Terra are hardly distinguishable during the Imperial era, Tellus was the name of the original earth Goddess in the religious practices of the Republic or earlier. The scholar Varro (1st century BCE) lists Tellus as one of the di selecti, the twenty principal gods of Rome, and one of the twelve agricultural deities. She is regularly associated with Ceres in rituals pertaining to the earth and agricultural fertility.
The attributes of Tellus were the cornucopia, or bunches of flowers or fruit. She was typically depicted reclining. Her male complement was a sky god such as Caelus (Uranus) or a form of Jupiter. A male counterpart Tellumo or Tellurus is mentioned, though rarely. Her Greek counterpart is Gaia (Gē Mâtēr), and among the Etruscans She was Cel. Michael Lipka has argued that the Terra Mater who appears during the reign of Augustus is a direct transferral of the Greek Ge Mater into Roman religious practice, while Tellus, whose temple was within Rome’s sacred boundary (pomerium), represents the original earth Goddess cultivated by the state priests.” 
Patricia Monaghan tells us: “The Roman ‘Mother Earth’ was honored each April 15 [Fordicidia], when a pregnant cow was sacrificed and its unborn calf burned. The Romans tried to offer appropriate tribute to each divinity and they felt that the earth – pregnant in spring with sprouting plants – would especially appreciate such a sacrifice.
Tellus’ constant companion was Ceres, the grain Goddess, and the two of them interested themselves not only in vegetative reproduction but in humanity’s increase as well. Therefore, they were invoked at every marriage that they might bless it with offspring. Tellus too was considered the most worthy Goddess on whom to swear oaths, for the earth, witnessing all doings on Her surface, would see that an oath taker kept his promise. Finally, Tellus, to whom the bodies of the dead were returned as to a womb, was the motherly death Goddess, for unlike Her Greek counterpart Gaia, Tellus was associated with the underworld as well as the earth’s surface” (p. 293 – 294).
On a side note, “the identity of the Goddess Nerthus, called Terra Mater, Mother Earth by Tacitus in Germania, has been a topic of much scholarly debate.” Click here to read a fantastic article by William Reaves entitled “Nerthus: Toward an Identification”.
Monaghan, Patricia. The New Book of Goddesses and Heroines, “Tellus Mater”.
Reaves, William P. ”Nerthus: Toward an Identification“.
Wikipedia, “Terra (mythology)“.
GardenStone. The Nerthus Claim.
Lipka, Michael. Roman Gods: A Conceptual Approach.
Took, Thalia. Thaliatook.com, “Cels“.