The mystery is solved.

In response to our intrepid reporter's email to Johnny Hart, we've learned that the mysterious words in the grass (with the exception of the May 21 strip, which our commenters below have noted was US Memorial Day) are the names of Hart's two grandchildren. They live far away from him and he has been putting their names in the strip as script in the grass "just to let them know he is thinking of them".

Very nice :) We don't know what the youngsters' names are, but that's the Hart family's bizness.

Thanks to JDB and the Two Peters, who did the detective work on this file.

Case closed. And it ain't often you get to say that in this topsy-turvy world

ronnie