Thanks both. gardenelf, there's a company called Netherland Bulb Company that sell trillium bulbs. I've also seen trillium in a Dutch nursery called Fransen Hostas, but they only had a couple. I find it very strange that you haven't been able to find any around where you are. That's too bad. Theodoros, you may like the plants but I guarantee you you won't like our weather conditions.
Thanks for the info, Droopy, I realise things must sound strange coming from a Dutch person . Even though I live in "the land of the flowerbulbs", my search for Trilliums has been limited. Because of my poor health I depend almost completely on the internet, and as you say, there aren't many companies offering Trilliums (at least, not the pretty one's). They just aren't popular at the moment, so they don't stock them in large quantities. I'm sure if Dutch gardeners were more aware of these special flowers, their popularity would increase. (If it hadn't been for the BBC's Gardener's World, I would never even have heard of these beauties!)
I don't find it strange at all, ge. I've come to realize that not all gardeners share my interest in woodland perennials, and few, if any, know about or take interest in trilliums. My mother and a couple of garden friends are always on the look-out for trilliums and have contacts that specialize in rare plants, so I'm pretty spoiled plant-wise.