How to get Melon seeds in Minecraft survival?

Meditate

Melon seeds are usually found in chests in mineshafts or nether castles. Like saddles for example.

According to the Minecraft site, melon seeds can be found in 18.8% of dungeon chests and 32.0% of chest minecarts in abandoned mine shafts in stacks of 2-4.

Or, just craft them using one melon.