You said it isn't coyotes but it sure does look like coyote poop to me. There is a persimmon trees next to us and the coyotes have eaten some of the fruit and I have seen the seeds from the fruit in their poop and it looks like the pictures you posted. My guess would be a pack of coyotes. Here they don't usually run in packs but I have seen some. If you have a camera put it up because whatever it was will most likely be back and was lurking looking for an opportunity and then you will know for sure what you're dealing with. Good luck..