A bulb the size of a lawn bowls ball.Grows a metre long spike with small blue flowers on the end. They dry and have small black seeds but the main bulb has smaller bulbs under its skin.This dries like an onion and sheds the small bulbs which take root if you don't pick them up! Very easy to grow and the small bulbs will start the process again from a very small size.

What?

Agapanthus????
Allium????

Where in the world is this.

https://www.google.co.uk/searc...

https://www.google.co.uk/searc...

Sounds like an Allium of some kind to me.

I was thinking the same as Celia and Silversurfer, maybe an Allium. I'm not sure which of the larger ones have offsets but some Alliums do. Lawn bowling balls are apparently 4-5" in diameter. RMAdamson, if you could post a picture it would help. Also what country you are in (presumably not USA because measurement given in metric) and whether this plant is growing in the wild or a garden.

Here are pictures of some alliums in tne NGA database, does it look like any of these?
http://garden.org/plants/brows...