Hi Dave!
I think you are right; I've seen this fern growing on Sabal Palms here in Florida, which is the palm it was growing on in the photo. I took that picture sometime last year and didn't get close enough to examine the fronds for sori but if I get a chance to get to that little park in the near future I will look. I'm 99.99% sure it is the Golden Polypody (P. aureum) which is a Fla. native.
Thanks so much for your help!
~ Lin