Rectangle shadow appearing over world (Shouldn't be there)

Hello; New to Unity.

I've got a pretty big world plane, and there's a shadow that appears over the world. I've looked around and there are no objects casting the shadow. It seems like the plane is casting a shadow on itself, but deleting it doesn't help; The shadow remains on the football field (see images).

Also, the shadow seems to move and disappear depending on where the camera is located.

Let me know if you need more info. I'm not sure what else to try.

-JM