In Kingdom Two Crowns, to get Stone, you need to progress to the second island. On the first island, Stone is not available. Here's how to get it:

1. Repair the derelict ship on the first island using Gold Coins and sail to the second island.
2. Once you arrive on the second island, explore until you find the Stone Mine.
3. The Stone Mine looks like two large stone pillars sticking out of the ground.
4. Pay 10 Gold Coins to activate the Stone Mine.
5. Once activated, it immediately starts providing Stone, which you can use to upgrade your buildings and defenses beyond the Wood stage.

The Stone Mine does not need to be defended, and it continuously supplies Stone for all future islands. Make sure to activate it on the second island as you cannot upgrade to the next resource tier (like Brick) without it. In summary, no Stone is found on the first island; reaching and activating the Stone Mine on the second island is essential to unlock Stone upgrades for your kingdom.