Using what I assume is an almond husk for scale this could be squirrel or wood rat. I am guessing squirrel by the almond shell and what you should go do is dig around in the soil of that pot, other pots to see if you can find buried peanuts or acorns.
The scale is still confusing and very important. What is interesting is you have had a very regular visitor that is comfortable pooping while eating probably perched on the rim of a pot?
You won't surprise a rat or mouse because they hide all of the time. Squirrels loved my pots that I had on my front porch. I am a weirdo that feeds animals and in an urban situation squirrels are the only wild animal thriving. So I fed squirrels and quickly got them used to being fed by hand. Squirrels are far more confident than rats. Rat poop is best found in basement, crawl spaces and anywhere they can utilize the insulation.
If you are able to find a smooth dusty surface or even LEAVE an innocuous dusty surface (assuming you have a porch roof) to get prints. Black background with flour thinly coating your thin, flat, 1'X1'? Set it behind your pots. Check on it within a day. If you get any track, take a picture with lighting that causes shadows, down low, not too bright and send it to us. I am better at tracking than I am deciphering poop. Take a picture of the pots with your poop pile. Take a picture after you've 'stirred' this pile just a little so we can see the color of older scat (on the bottom) versus newer scat usually wet with urine that is darker. Believe it or not this is an important way to distinguish between OTHER types of these scats. (I might ask you to dissect a pellet and pull it apart to be able to check out what it has been eating and or possibly finding hairs from grooming itself or brood, do you have a good magnifying glass?).
My (grins) squirrels never pooped on my porch much less in a pile like this. But something is A REGULAR VISITOR. And where is it that you live? In the country surrounded by acreage? What wildlife do you have visiting? Are you in suburban or urban environment? Do you or neighbors have compost piles? Do you have a weirdo neighbor like me putting out food? Anyone near you have a parrot as a pet? Bird feeders (for parrots)? The answers to these questions would really help.
Also, please send pictures with a nickel or dime or quarter for scale.
Check these sites for your own comparison; verbal descriptions of scat
pictures of scat comparison
scat and tracks
I am thinking squirrel as this seems to be lighter than rat. Rats would not be doing this out in the open so blatantly. Squirrels would and this site says that the droppings of squirrels are lighter than rats...did you do the little tile and flour thingy?