What small animal/vermin has poop that is small (less than 1/2"), thin (like a worm) and has a white dot?

I have a small court yard infront of my house which is enclosed by a waist high brick wall. Every morning there are about 5 - 7 of these poops there. There is ivy in the planter which is in front of this wall so I thought perhaps that these were mouse or rat droppings, but I put rat poison and rat traps with cheese on the wall and the droppings continue - even in the poison tray! And the cheese on the traps was never disturbed.