This seed spawns you in a roofed forest, or more accurately, on a roofed forest. When you spawn you’ll see you’re right on top of a giant brown mushroom. If you get down from that perch, you can explore the roofed forest what you can find among the large mushrooms and close trees. If you go to the left of the spawn point, you can even find an abandoned mineshaft.
Minecraft PE 0.15.0 Seed: -252487356
Keep going left through the roofed forest until you come to a small clearing with a river nearby and a cave opening in the middle of the grass.
If you do down into the cave, it will open into tunnels that go in many directions. If you face the direction of the river, one of the lower left openings will lead you to the abandoned mineshaft. Quite a few of the other tunnels lead to it too. So if you can’t find it, just keep trying different directions.
Keep exploring the mineshaft and try to find rare ores like gold. Mineshafts are a great place to find them right on the walls and floors. You can also find minecart chests which hold rare items.
A dungeon connects to the mineshaft in one section, giving you more opportunity for rare items. It’s hard to explain where it is since the Pocket Edition doesn’t have coordinates, but once you’re in the mineshaft, try to head in the direction of the river on the surface and a little to the left.
Eventually, you should see a bit of cobblestone and mossy cobblestone on the ceiling. Inside you’ll find a spider dungeon with two chests.
The most noteworthy items in the chest are enchanted books, a name tag, and iron.
I hope you can find everything in the mineshaft, and perhaps you’ll find even more than I did. Happy exploring!