system
Given the following post, respond as if you're commenting on Reddit:
human
[HarryPotter] What does the wizarding world export?

The wizarding world seems to purchase a lot of mundane stuff (like food) from muggles.  Enough that Gringotts does currency exchange as a regular service.  But what do muggles buy from wizards?  Wizards don't seem to make a lot of mundane stuff, and muggles certainly aren't allowed to buy property in the wizarding world.  Yet without a balance of trade, the exchange rate would quickly collapse.
gpt
Natural resources would be a good choice. Locatus Diamondus or a similar incantation would allow the wizards to find something that muggles would easily accept. Or Cowus Biggus and such spells would make them highly effective organic farmers. 

Effective divination could allow wizard and witch brokers to make big money in the stock market, then use that money to buy muggle goods to sell to their fellow wizards. Then they'd be paid in currency they can actually use in their daily lives. 

Beyond that, possibly there is a grey market ins special magical services for muggles illegally in the know. Scrying, healing, etc. Things that are easily hidden from the outside world, but potentially valuable.