I want to create a random polygon shape for my biomes in a tile map. The tile map is created using perlin noise, so on top of that I want maybe two or three polygons which I can use to set the tiles of the map to the correct biome.
Has someone come up with a way to make a 4 sided random polygon in monogame? Or is there maybe a better way to create random biomes using colors in the person noise?

There are some very cool ideas here about generating random polygonal maps here. It's quite a complicated topic, but might give you some ideas.

There's an interactive demo as well