Sorry, I don't have enough wall space for a blackboard. I have saved lots of notes like that from my oldest Granddaughter. She use to write them all the time. I put them in my keepsake box.
I keep a small memo pad in my car. One day I opened it to get a scrap of paper and found a sweet note from my son. Have kept it there since and look at it when I need cheering up. So nice to be loved...