You ask the shopkeeper if she can tell you about runestones.

Shopkeeper: "Yepper pepper! Runes are like, magic rocks. When they have an inscription thingy, you can smash them to cast spells!"

Windcaller: "I... don't know any scribes here in Hoofington, but... perhaps you can find one in Ponyville."

Moonflower buys a bottle of strawberry shampoo.

Moonflower: "So, you found anythin' ya like? You can use some of my bits if you're short!"