I wanted to have ground under my door and I thought it was important to include it so that the door looks more like I intended it to. I want it to look like a portal into another world and in order to really make this clear I wanted to have it on a grassy hill with no walls.
First of all I created a large sphere under the door
I then selected the bottom half of the sphere using face mode and deleted them to make the rough mound shape.
I then used the edge tool to reduce the number of subdivisions (remembering to delete vertexes too) and I pulled edges out to make the ground uneven and more natural. I also flattened off the top for the door to sit on.
