Lots of discussion about the poop bomb, so I thought I should update.
Mr. Ashley is the one who picked the poop bomb up and he said it wasn't big enough to be Lily poop and not small enough to be Murphy poop. Also, there's a new space between two trees in the back hedges--I think our backyard neighbor leaned through and tossed the bag into the yard. They threw it where I would normally suspect the next door neighbors, but they have a very big dog, and she's a teacher and they have older kids and seem nice, and I think it would have hit the orange tree and fallen elsewhere if it came from that side. The trajectory path seems more likely for the backyard neighbors, especially with the new space in the bushes.
So all signs point to the owners of the fat Cocker Spaniel and it may not even be related to any issues relating to our dog's poop, since it doesn't appear to be our dog poop that they threw into our yard, they might just hate us since our dogs bark at each other whenever they are out at the same time and our kids are loud. The last renters here were non-pet owning Mormons with one small daughter and a baby...so I'm sure we really suck compare to them.
The only logical recourse is to use the potato cannon (yes we have one, don't ask) to launch cat turds into their unscreened pool.
It's unfortunate that it has come to this so soon.