Nearly 90,000 ceramic poppies at the Tower of London this year.
I can't find an origin for this affecting picture but it seems to have been used by a wide variety of organisations, often in connection with quotes from 'In Flanders Field' by John McCrae.
This seems to be a poster to advertise poppies for Memorial Day in the US (I hope I have that right, that's what Google suggests).
And this is an alternative to the poppy in the buttonhole on sale for Remembrance Day that I bought the other day.
Lest We Forget