Daisies are often regarded as a symbol of innocence, and picking daisies is therefore reminiscent of time spent in innocence and innocent pleasures, not just a personal indulgence, but time spent away from all the worries and problems and jaded outlook that come with experience, knowledge and age, and away from the drudgery of day-to-day life. So although you can "be" now, and enjoy your everyday life with such awareness of existence, the daisy picking is a return to the essence of an imagined perfect childhood, oblivious to the darkness in the world.

...Now that was a bit deep for me at 9.45 am. And, of course, my views do not represent the views of affiliated daisy picking people in any way. And perhaps the old lady genuinely did want to pick actual daisies. That's just as nice as picking metaphorical ones.