Toadstool or Hobbit roof for a stump.?

I'd pick the toadstool, but that's just my own preference.

Basically, you need a shallow bowl-shaped something for a topper, which you paint with exterior enamel. Without knowing what you have access to or what tools and skills you have, my best suggestion is to look at items set out for trash collection, especially those made of wood or metal. I've seen this done with one of those metal snow saucers, but that was long ago when kids had those.

Inverted satellite dish.

You can try Lowe's or Stine's.😊