Could they be Camassia quamash?

Thanks lauraann, you're good. I did a google search to look at some pictures and get info on camassia quamash and it looks like that is what I have. The info said they come from bulbs though, so I'm not sure how they got in my garden. Obviously they didn't grow from some seeds the birds dropped in my yard.

Check you neighbors gardens. It's possible that squirrels dug up the bulbs and buried them in your garden. Also many bulbous plants do produce seeds, particularly those in the lily family, like camassia quamash, and it is possible that the seeds were dropped by birds or other animals. In any case, that's great that you were able to obtain camassia quamash plants with out any effort on your part. They are beautiful plants.

jeannek, thanks for the suggestion. I did check out my neighbor's gardens and don't see anything that looks like what I have. The squirrels still could have brought them though, they seem to be running around in my yard all day.