Could be one of the Bracken Ferns (Pteridium acquilinum)

Looks like a lady fern but would need a better picture to say for sure.

And here I was going to say Dryopteris.

OOOo! I love a mystery....I'm going to stick a piece of paper under the leaf to separate it from the rest of the foliage around it!

You could also take a picture of the back of the frond; arrangement of the sori on the back can help distinguish it too.

close-up #1

I think this is the same species (?) growing on a rock. I will go in search of a sori close-up. Thanks esh!

The sori...any guesses :) ?

Certainly looks like it could be lady fern then.

Thanks Esh! At least THESE aren't invasive :)!

This would be the green stemmed form; there is also a red stemmed form.