Cat litter not in the box

Just noticed today, about 10:15 that there are cat litter balls out in my yard. Yeah, I woke up about 9:15 am and was having my morning coffee and happened to look out the kitchen window. Low and behold, I spot some of those cat litter balls in the bushes next to the garage. And I saw some in the cracked concrete sidewalk out side of my house. Those cats next door are not, at least I don't think they are bringing those things over and putting them in my yard. I think she, Doris is doing it. Gonna find out later.