Acanthus spinosus is an herbaceous perennial. There are other species but this is my favourite as I prefer it's more dissected, thistle-like leaves. A mature clump in flower is an impressive site. Scroll down this board for further details.
Pieris japonica 'Flaming Silver' The other two near the Kerria are Pieris - I wasn't certain. Not sure which cultivars you have, but it looked like they were happy were they were. Not suggesting you move them, just thought you might want the name.
Lobster Claw* A fast-growing herbaceous perennial with stalks reaching 7 feet tall. Scarlet and yellow bracts emerge on second-year stalks. Plant in bright shade with moist, well-drained soil. USDA Hardiness Zones: 10B to 11
‘Ivory Prince’ Helleborus hybrid ‘Ivory Prince’ has dark red-pink buds that bloom creamy white and age to a mix of burgundy and light green. Blooms Opens creamy white from late winter to early spring Size 12 to 15 in. tall and wide Cold-hardy USDA zones 4 to 9 Heat-tolerant AHS zones 9 to 1 Source Plant Delights Nursery, Inc.