I think it was a Cthulhu Now adventure that I played 20 odd years ago. There was a presence in a cornfield, and it could reanimate dead bodies. I seem to remember loads of twitchy dead rabbits, birds and small game. I think the field blocked the way to an important building and we used a butchered pig to test our theory, it got into the pig and animated it...
I don't remember the exact details, but I'd like to read the adventure again - do you recognise this?
Sorry if my description is a bit vague, but it was a long time ago - hope you can help!