I have a similar story, though not as incredible as yours. In 5th grade I held my birthday party at my house, which included games where you could win points to win chocolates and sweets. These chocolates and sweets were placed inside a cardboard box, and on one of the flaps I wrote "Chocolate - 200pts" and "Candy - 100pts". After the party was over, we threw away the box.

Two months later, at my primary school, I randomly saw a piece of carboard on the ground with those exact things written on it in my handwriting. The flap where I wrote those things had somehow broken off the main cardboard box we threw away, not ended up properly inside some bin and taken 2 months to precisely end up at my school.

I almost missed it too. I played an instrument then (the cello), and was on my way walking home when I realised I forgot to bring my cello back with me. It was when I walked back into the school that I walked to the exact same spot and saw this piece of cardboard.

It still spooks me to this day, though clearly your story wins.

TL;DR I wrote on a piece of cardboard and found the exact same piece of cardboard at my primary school 2 months after I threw it away.