According to Wiki (https://en.wikipedia.org/wiki/Lavender%27s_Blue) "dilly dilly" is no more than a variant of what was once "diddle diddle" - in other words it doesn't really seem to mean anything. We also learn that when first printed it was "to be sung to the tune of Lavender Green", so that must have been an older version of the lyric. All very strange since in my experience lavender is neither blue nor green but kind of ... lavender. Amazing how bulletproof these really old songs are - one reason they've survived all this time is that you can do just about anything to them and always they live to fight another day. Fun post - thank you.