Yes I would agree with everyone so far, in that your plant is in fact a Calla Lily, otherwise known as an Arum Lily or Zantedeschia Aethiopica,
These hardy perennial plants, are fairly low maintenance and are often grown in flower beds, containers or even as indoor plants. They require well drained, but moisture retentive soil, with plenty of moisture and fertilizer during the growing season.
In warm climates, although these plants require full sun, they often prefer a bit of light shade in the afternoon.
These Lillies normally bloom in late Winter right through to end of Spring, which is when they normally start to die down and are best left to bake in the soil during the Summer months, after which, the Autumn rains normally reactivate the plants and the whole process starts all over again.
There is however, one very important thing that anyone with pets or children might wish to be aware of, when growing this plant, and that is - Calla/Arum Lillies are known to be toxic, with the roots being the most dangerous part, but the whole of the flower is also poisonous,