Large flowering crocus
The crocus is very versatile bulb, which can be planted just about anywhere, from tiny pots to great carpets of colour. Like snowdrops and bluebells these are most impressive when planted in large numbers. In late February or early March the contrast that crocus will give flowering against yellow daffodils is superb.
If you want your crocus to naturalise in grass, the quickest and most effective way is to use a spade to cut under and peel back the turf.
Roughly break up the soil and scatter the bulbs randomly, then simply roll back the turf. Be sure to avoid mowing the grass for a couple of weeks after flowering until the foliage has died back.