When the Witches first appear in act 1, scene 1 of Shakespeare's Macbeth, they're not carrying or wearing any objects or talismans. They do, however, refer to their "familiars"—evil spirits which are usually in the form of a small animal like a toad, bird, dog, or cat and serve as a witch's demonic companion or attendant.
FIRST WITCH. I come, Graymalkin.
SECOND WITCH. Paddock calls.
THIRD WITCH. Anon! (1.1.9–11)
"Graymalkin" is an affectionate term for a gray cat, and "paddock" refers to a toad.
The Third Witch doesn't identify her "familiar" until act 4, scene 1, when she calls it a "harpier," or harpy—a flying monster with the head and upper body of a woman and the tail, wings, and talons of a bird of prey.
THIRD WITCH. Harpier cries, “’Tis time, ’tis time.” (4.1.3)
The Third Witch wins the prize for most horrifying familiar.
These “familiars” symbolically help to represent the “weird sisters,” as they call themselves (1.3.33), as witches.
In act 1, scene 3, the First Witch is seen to have, if not a symbolic charm, then a grisly souvenir.
FIRST WITCH. Look what I have.
SECOND WITCH. Show me, show me.
FIRST WITCH. Here I have a pilot's [sailor's] thumb,
Wreck'd as homeward he did come. (1.3.27–30)
Although a cauldron in which to brew their potions might not be something that the Witches ordinarily carry around with them, cauldrons are symbolic of witches in general, and particularly of the Witches in Macbeth.
WITCHES. Double, double, toil and trouble;
Fire burn and cauldron bubble. (4.1.10–11)
There's an interesting stage direction that appears in this scene in the First Folio of Shakespeare's plays, published in 1623. The Three Witches have just finished brewing up their potion and cooling it off with "baboon's blood" (4.1.37).
Enter Hecat, and the other three Witches.
(In later printings of Macbeth, "Hecat" is "Hecate.")
The other three Witches? The original Three Witches have been brewing their disgusting potion for thirty-seven lines, then Hecate shows up with three more witches? Where have these other witches been all this time, and why do they choose to crash the party at this particular moment?
Modern editors change this stage direction to read “Enter Hecate to the other three Witches,” or simply “Enter Hecate,” but it’s interesting to speculate whether this is a printing error or if three other witches actually appeared on stage during the early productions of Macbeth.
There's another implied stage direction in this scene.
MACBETH. ... Why sinks that cauldron? and what noise is this? (4.1.119)
It's easy enough to explain the noise, because “hautboys” (oboes) start to play, but where is the cauldron going?
Scholars believe that there were trap doors in the stage floor of Shakespeare's Globe Theatre which led to an under-stage area called the “cellarage,” which was nicknamed “hell.”
The stage floor was approximately five feet above ground level, so actors and stage hands could move around under the stage. The ghost of Hamlet's father likely ascended from and descended into “hell” through a trap door, and it’s possible that the cauldron—or even the Witches themselves—might have appeared and disappeared in the same seemingly magical manner.
The coming and going of the cauldron can be seen to symbolize the mystical, supernatural powers of the Witches.