The confusion with Shamrocks stems from American florists selling Oxalis acetosella or a similar species like the purple leaved variety above as "shamrocks" in fancy foil wrappers around St. Patrick's day, like they do poinsettias around Christmas. The term 'shamrock' comes from an old Irish term, and I'm not certain but I suspect it was used for both trifolium and oxalis, which both occur there. They are similar in leaf, but from very different families with very different flowers.
The white dicentra pictured above is probably Dicentra spectabilis alba. If you ask your local florist (I am assuming that is what we in the US call a plant nursery?) for that, you'll have better luck. You could also look for seeds, though I never saw any develop on my plants when I had it. At least here in the US, it's pretty easy to find mail order too, on the internet.
Viirin's pic of a violet is a sweet violet (Viola sp, probably V. sororia). African Violets are Saintpaullia in the gesneriaceae, again, completely different families and not at all closely related. The violet in the pic is closely related to the garden pansies already on the site though. There are hundreds of Viola species and cultivars to choose from, with flowers in almost all colors of the rainbow, including black.
Waterlilies would be fun, but then we would just have to have a pond, with other pond plants to go with it, right? Cattails and marsh grasses around the edge, as well as things like Lobelia cardinalis, swamp lanterns (Lysichiton americanus), monkeyflower (Mimulus guttatus), lady fern (Athyrium felix-femina)... lots of cool water plants to choose from, and could be a whole room of its own. But maybe that is too much to ask? lol