From the Super Mario Wiki

It has been requested that additional images be uploaded for this article. Remove this only when the image(s) have been uploaded for this article. Specifics: Images for all styles other than NSMBU

A 30-Coin from Super Mario Maker 2 (New Super Mario Bros. U style)
A large coin that has the number 30 written on it

First appearance

Super Mario Maker 2 (2019)

Effect on player

Awards the player 30 coins.

30-Coins are gold coins found in Super Mario Maker 2. As the name suggests, when collected, they grant the player thirty coins. They appear as a variant of the 10-Coin, in addition to the 50-Coin.