They are indeed a beautiful flower, clo
And what a lovely surprise it must have been to find those flowers amongst your grandparents' old letters.
Its scientific name is Myosotis arvensis, but I can understand why the Alzheimer Society might use the flower as their symbol, because the common name for the flower in English is "Forget-me-not", although this may just a direct translation of the name it had already been given by the French: "Ne m'oubliez pas", or perhaps from the German: "Vergissmeinnicht".
This flower has been adopted by several associations, including Newfoundlanders wishing to commemorate their fallen from the First World War, particularly the Battle of the Somme where so many were lost.
I actually have a few of them flowering in planters outside, grown from commercial seed. I might try to take some macro shots of them in the next few days (if I can remember which box my macro lens is hiding in).