In his Greek Myths, Robert Graves writes that Demeter (in disguise) was the guest of King Celeus in Eleusis. The lame daughter of the King, Iambe, "tried to console Demeter with comically lascivious verses, and a dry nurse, old Baubo, persuaded her to drink barley-water by a jest: she groaned as if in great travail and, unexpectedly, produced from beneath her skirt Demeter's own son Iacchus, who leapt into his mother's arms and kissed her." (Robert Graves, The Greek Myths. (London: Folio Society, 1996) 2 Vols. Vol 1, p.92) Graves writes, "Iambe and Baubo personify the obscene songs, in iambic metre, which were sung to relieve emotional tension at the Eleusinian Mysteries; but Iambe, Demeter, and Baubo form the familiar triad of maiden, nymph, and crone. Old nurses in Greek myth nearly always stand for the goddess as crone." (p.96)
The following excerpt is taken from Clement of Alexandria's Exhortation to the Greeks translated by G.W.Butterworth
"Baubo, having received Demeter as a guest, offers her a draught of wine and meal. She declines to take it, being unwilling to drink on account of her mourning. Baubo is deeply hurt, thinking she has been slighted, and thereupon uncovers her secret parts and exhibits them to the goddess. Demeter is pleased at the sight, and now at least receives the draught, – delighted by the spectacle! These are the secret mysteries of the Athenians! These are also the subjects of Orpheus’ poems. I will quote you the very lines of Orpheus, in order that you may have the originator of the mysteries as witness of their shamelessness:"
"This said, she drew aside her robes, and showed a sight of shame; child Iacchus was there, and laughing, plunged his hand below her breasts. Then smiled the goddess, in her heart she smiled, and drank the draught from out the glancing cup."
The figures usually had elaborate headdresses and some hold cups or harps. Some figures have a suspension loop moulded into the head which seems to indicate that they were suspended in some way possibly as some sort of amulet.
The following two books are mostly about medieval sexual sculpture but both have sections on Baubo