Mushroom biomes are quite rare to find close to spawn normally. But in this seed you only have to do a little bit of swimming to come to a huge mushroom biome.
Found by: TelepathicGrunt
The spawn is on an island but just continue straight forward across the water and you will find the mushroom biome.
As you come closer to the mushroom biome you will realize how large it is. It’s a ton of space to explore!