Thanks everyone for your suggestions. After looking at the pictures I agree it
could be either the allium or agapanthus. I'd need to see both plants close up
to make a call. Stephen, does the agapanthus also grow from a bulb? I suppose
I could go looking for a bulb if it doesn't and that would make for a good ID.

Either way, these guys are beautiful. I don't know where they came from.
Either blown in seed or some squirrel burying bulbs?

Thanks everyone,
Laura B.

I agree it is an ornamental allium. However, there is a very similar
plant that is grown in gardens: Agapanthus or "Lily of the Nile" from
South Africa.