What is this poopy crap in my back yard?

My educated guess as to what this poopy crap substance in your back yard is that it is poop. Most likely from an animal. Poop is a bodily waste excreted from the body in a solid or liquid form. Poop is very natural and I wouldn't concern yourself about it as it is biodegradable and will remove itself from your lawn with time. For faster removal you could pick it up and throw it away. I hope this has helped