For the prompt “Anonymous” two things came to mind: a silhouette (that is commonly the profile picture of an anonymous account), or the concept of something being left behind. I thought shoes would work well, since shoes aren’t something people often bring with them/usually don’t choose to leave behind, and it would make someone think “who do these belong to?”
I took a number of different photos across the house (my mom has a lot of shoes), and ultimately I decided on this photo where I was standing in the yard and chucked off my own pair of shoes. I liked it better than all of the other photos I took.