Thanks

So today I am just sitting here a home, paying a few bills and playing with my sweet baby Cora. Well someone knocks on the door. I get up to answer it but since I am still fairly handicapped and gimpy, it takes me a while to get there. By the time I arrive at the door, there is an envelope being pushed through the crack. I have just enough time to look through the peep whole to see a woman, one I do not recognize, walking away from our door. I open the blank envelope and inside I find a piece of white paper with only the words "thanks" written in pencil and $15 dollars in cash. I am racking my brain trying to figure out with this is in reference to and I have know idea. Was it given to us by mistake? We will probably never know. But hey, thanks!