Dragon Coin

A Dragon Coin (also known as a Yoshi Coin) is a large coin that first appears in Super Mario World. It has a picture of a Yoshi's head imprinted on it.

Super Mario World
There are at least five Dragon Coins littered around most levels in Super Mario World (some levels, such as Castles, Ghost Houses, and Fortresses, have no Dragon Coins in the original SNES version). Collecting each one counts as one coin while it makes a unique sound effect from other coins. The first four coins collected in the game results in 1000, 2000, 4000, and 8000 points, respectively. Collecting five of them is the equivalent of collecting 100 Gold Coins, awarding an extra life for the player. On rare occasions, one may encounter six or more Dragon Coins in a single level; in these cases, every Dragon Coin after, including the fifth, awards an extra life. In these types of levels, going through a Warp Pipe to a new area causes all remaining Dragon Coins to disappear if Mario or Luigi has already collected at least five of them, making the remaining ones unobtainable. Chocolate Secret is unique, because it contains only one Dragon Coin in the SNES version of Super Mario World, for unknown reasons. Yoshi's Wings can be used to access certain auto-scrolling Coin Heavens where five Dragon Coins can be found.

Super Mario World 2: Yoshi's Island
Dragon Coins were originally going to appear in Super Mario World 2: Yoshi's Island, but they were most likely replaced by Smiley Flowers due to them being mechanically similar. The sprite for them were completely removed from the Game Boy Advance port, Yoshi's Island: Super Mario Advance 3.

Super Mario World: Super Mario Advance 2
In Game Boy Advance port of Super Mario World, Super Mario World: Super Mario Advance 2, Dragon Coins have a slightly bigger role, having been added to levels that did not originally have them including Ghost Houses, Castles and Fortresses. The number of Dragon Coins acquired is recorded on a menu, and if the player collects them all, a cutscene will play showing all of the collected Dragon Coins falling from the sky and being stacked together. Afterwards, a giant Dragon Coin appears, and Yoshi eats it and lays a Yoshi's Egg, which hatches into a giant coin with Peach's face, resulting in all of the Dragon Coins in the game having Peach's face imprinted on them instead of Yoshi's.

Game & Watch Gallery 4
In Game & Watch Gallery 4, getting five KOs in Boxing earns a Dragon Coin.

Super Mario World

 * Wii U Virtual Console manual description: "Collect five Dragon Coins in a course to earn an extra life."

Trivia

 * Most of the games in the Yoshi series such as Yoshi's Safari, Super Mario World 2: Yoshi's Island, Yoshi's Island DS, and Yoshi's New Island feature Coins having a Yoshi's head shown on them rather than having the normal Mario coin design, making them resemble smaller Dragon Coins. The Coins in Yoshi's Crafted World feature a depiction of a Yoshi Egg instead; however, the larger 10-Coins do depict Yoshi's head, resembling the Dragon Coins even closer.
 * In the Nintendo Power Advance Guide, the symbol for the Dragon Coins is drawn with a three-tined fork instead of Yoshi's or Peach's likeness.
 * The sound effect for obtaining an Advance Coin, Star Coin, and color coin is the Dragon Coin sound effect from Super Mario World: Super Mario Advance 2.
 * In New Super Mario Bros., the same sound effect is labelled as "SE_OBJ_GET_DRAGON_COIN", further suggesting that they replaced Dragon Coins in the final game.