Fritillaria imperialis

They need a deep, rich, well-drained loam soil and a warm, sunny position where they can be left undisturbed for many years. If your soils are prone to water retention plant the bulb on a layer of grit. Plant them nice and deep, at least 30cm deep, even more in lighter soils or augment with better stuff. It is claimed that planting the bulb on its side may prevent rot when the bulb is dormant, but they probably right themselves anyway. In the wild, a photograph in Chris Gardener's book "Flora of the Silk Road" they are shown en masse in a clay seep, with water running freely over them. Avoided by sheep they do quite well, and show just how tough they are. This site does dry in summer though, so any amount of water during growth is probably just fine. 

For inspired planting Margaret Barker has them planted inside the block of azaleas with heathers in front and various other spring bulbs for seasonal interest. perfect and simply beautiful. 

These are yellow or orange. I aim to get the colour correct by judging the pigment in the leaves. No guarantee.

Image: Hans Simon Holtzbecker, Public domain, via Wikimedia Commons