Paeonia lactiflora 'Festiva Maxima'
Pure white double blooms flecked with crimson at the center. Beloved since 1851 and still unmatched.
The ASPCA lists peony (Paeonia officinalis) as toxic to cats and dogs, and to horses. Eating it can cause vomiting, diarrhoea and listlessness. The ASPCA names that one species, but ours are the same genus, so give them the same caution, and keep a vase of cut stems out of a cat's reach.
For gardeners who like to stay ahead.