Your grandchildren are so beautiful!
I would get silk flowers that have individual mini flowers on each stem, for example a lilac is made up of all little
tiny flowers, or baby's breath, or something like that, and sew the flowers by the school and on the pathway on your wall hanging. You could use a lazy daisy stitch for the leaves. That would make it very colorful and dimensional.
You could add some beads, too, to look like different flowers.