Anyone know the name ?

A friend dug up some of these huge bulbs from her garden several years ago and gave them to me, I planted them in large pots to enable me to keep them in the Greenhouse in the winter, our garden is far more exposed than hers is. I have never known what they are called, neither does my friend, they look as if they belong to the lily family. If anyone knows their name I would be delighted to know.