A good seed to start survival, you will spawn on a mushroom island with mines, so you will have a supply of food from the very beginning and the opportunity to get another valuable loot. You will not find open passages in the dungeon, but the tunnels are quite close to the surface, so you can start digging anywhere and very quickly get to them.
How to use Mushroom Island with Mines seed
Start the Singleplayer mode
Select ‘Create New World’
Then click on ‘More World Options…’
In the ‘Seed for the World generation’ field, enter 399942533753735804