Covering mostly European stuff, heavily Scandavian, things that people practice would actually have used in a bag. Though when she asked what our interests were, most of us were writers not gamers, and I mentioned the contrast between Gandalf with his staff, and Conan's sorcerers with their towers full of stuff, and we did a brief excurse into towers, which she deemed impractical; most of her lair would be underground. (In a dungeon! 0:)
You would have something related to thunder. Like a Neolithic axe hand. To invoke all the powers. Oak stuff would also be related; oak is much more likely to be hit by lightning than other trees. Acorns on the windsill were used to ward off evil. The thunder god tends to be the big god.
Stuff would have mystic-looking writing, even if the magician had just devised it.
Lead tablets. You would inscribe writing on it, and the spell would last that one. Gold was too expensive, and copper and silver would corrode. So, lead. The best lead was stolen from church windows. I mentioned that ancient Roman text told you to use stolen lead, from the water system. She talked more about that. Stolen goods -- like making a cake from flour stolen from three households.
You could fold up lead tablets to form a bee, and drop it into the water. That would sink, and let you let the cow drink it, with the bee draining off the evil. One audience member wanted to know if it cured cows. I pointed out that most problems were self-limiting, and she added that you could always try something if the first didn't work.
Curse tablets. I told about a spring where people would donate stolen goods to the goddess and invoke her rage on the thief. She observed that there were a lot of those. Back to Egyptian times. You would donate it to the Furies, say, or the spirit of a dead murderer, perhaps, to invoke the rage of the new victim on the thief.
Beeswax tablets -- two pieces of wood, hinged together, and hollowed out, so you could pour in beeswax and write and then smooth out. Then, you could write something under the beeswax, too, and hide it, so you had a spell under your grocery list.
She mentioned that if you say at a party that you read hands, to anyone, shortly you will read everyone's, and you can eyeball them for physical signs, like your fingernails, to judge.
String was also used a lot.
Needles. You got a needle that had been used to sew a shroud, and put it in a bit of shroud cloth, and wrapped it up to keep it from piercing anything else, before using it on the clothing of a successful gambler, so you won instead. Though if you found it in yours, you would have to pull it out without using your fingers and throw it in the fire, and then cut out where it had been and burn that, too, and patch your clothes.