I believe that it is Boston Fern, Nephrolepis exalta.
You can check the roots to see if there are any little balls on them.
This fern is very invasive. I have some in my backyard.
One thing about it though. It is easy to contain! I just yank it up and toss the plants. Do not mulch it unless you trash the little balls as they will grow new plants!

Thanks! When I pulled the ones out of my yard it did have the little balls on the roots. Is there any way to contain it to the flower bed other than pulling out the wayward fronds? I don't have any physical barrier down right now--the bed is just edged with the weedeater to keep the grass separate.

Also, if I did want to plant some further down in my flower bed, would I just pull the frond out with the ball attached and re-plant it or do I need to do something special to the root?

De

If its agresive at one end of a flowerbed it will probably be that way at the other end. Why not go for a different species.

I don't mind it filling just the flowerbed--I mainly want to keep it out of my grass.

De