Flowers, how about Silver Mound/Wormwood Artemsia..It's hardy from zone 3..Toni

My most silvery-white foliage is Centaurea gymnocarpa 'Colchester White". Teucrium fruticans has small steel-grey/green leaves on white stems. These are two new favorites that I've had good luck growing in ordinary soil, full sun...not bothered by our humidity or frequent rains this spring. Eucalyptus neglecta (Omeo Gum) has grey-blue round leaves... I intend to keep this stooled to shrub size by cutting for vase use. Needs full sun.

A silver-grey delight is Dichondra argentea 'Silver Falls"..it's a creeping groundcover which is lovely trailing over a pot or wall. It is not hardy but can be carried over inside. Will take full or filtered sun, ordinary soil.

I have a large old Rue plant, Ruta graveolens, which has powdery-blue foliage...another favorite for cutting. And a gnarly old Rosemary which is grey-green in spring growth but grey-blue later in year...some selections are more grey or blue than others. Both Rue and Rosemary require full sun and excellent drainage.

I grow a small spiky Blue Fescue and a taller blue wide-leaved grass (not sure of name). And there's a blue Juniper aptly named 'Blue Star' which is a low-growing groundhugger but I grow in pot.

Sedum sieboldi has rounded dime-size leaves of grey-blue, which turn burgundy-gray in winter. Couple of Sempervivums are grey-green with red tones.

Oh, you might also like Ophiopogon 'Blackie' and the Black-stemmed Bamboo, Phyllostachys nigra.

And Sarmentosa saxifraga has grey-green fuzzy leaves, a groundcover which will dangle new baby plants on red stems over side of pot or wall.

All the above I grow in containers, usually combined with other plants in a large pot or cedar planter-box, outside year round except for Dichondra (though I intend to test its hardiness this winter). All easy-growers, no diseases or pests. I do have to handwater the containers, but I rather enjoy the "dawn-patrol" in summer. They can of course also be grown in-ground. josh