(Not a poo troll. Happy for MNHQ to confirm if necessary.)
Well, let’s say, I certainly don’t think an animal has put it there.
There is lots of it. Not in a pile like an animal would do but dotted all over the yard and on the terrace like it’s been flung. And it’s a collection of poos. Not all from the same “movement”. Possibly not all from the same animal. Some lighter, some darker. The location of my yard means whoever has done it has either sought out my house, found the back entrance through a lane, come down through my garden, down my steps and flung it onto my yard. (Diagram included 
) Or one of my neighbours has done it. Obvious suggestion would be a neighbour. But I don’t know why either would do this. I have cats and they do go outside. They don’t go into neighbour 2 garden at all as they have a dog. They do go in neighbour 1s garden to sleep under the hedge but so do the dozen other cats on this street and he also looks after his friends cats too on occasion which go in his garden so if there is poo there it could be from any one of the cats around. Mine also use a litter tray in the house and without wanting to be graphic- the poo in the yard is bigger than their poo. I’ve lived here several years and neighbour has never mentioned the cats being a problem. It would be difficult for neighbour 2 to have done it from their side too as where some of it is wouldn’t be possible from where they would have to throw it. Perhaps there is a magic poo fairy that delivers gifts that nobody wants? 
I’m thinking of getting a camera up to catch the culprit if it happens again.