It seems that nobody replies.
I believe that you call hart tongue fern the Asplenium scolopendrium. It is a fern too common in my area so it is not proposed by gardener.
Along the rivers there are some specimens very spectacular but they are protected, however I have some of this ferns in the garden were born spontaneously.

Unfortunately i'm living in Italy and it's impossible send plants in the USA.
If you want to try to sow the spores it is easy to send them in an envelope and in a few weeks I think that the spores are ripe.
If you are interested you can contact me on my page.

The website I reference below appears to still be little known; sometimes I selfishly think that's a good thing! They list a few East Coast sources but are not, of course, updated with recent availability. In theory, every listing is either mail order or wholesale.

Earthly Pursuits, Inc. Windsor Mill MD USA Web Site
Fern Factory Anaheim CA USA Web Site
Forestfarm Williams OR USA Web Site
Fraser's Thimble Farms Salt Spring Island, BC, V8K 1A3
Canada Web Site
Glasshouse Works Stewart OH USA Web Site
Gossler Farms Nursery Springfield OR USA Web Site
Mason Hollow Nursery Mason NH USA Web Site
Siskiyou Rare Plant Nursery Talent OR USA Web Site
Well-Sweep Herb Farm Port Murray NJ USA Web Site

I started collecting the spores of Harts tongue fers and I think I can sent them in a few days.

Growing ferns from spores is not difficult, requires very little work but a lot of patience.

I started to grow ferns from spores only last summer, I am an apprentice, but things are working well.
I sowed spores of Osmunda regalis, Platycerium bifurcatum, Dicksonia Antarctica, Cyrtomium falcatum, Polystichum setiferum, I apologize for the Latin names but I do not know the corresponding names in English, and are already growing young ferns.
The spores of Adiantum venustum and Onoclea subtilis have sprouted but are still at the stage of protalli.

f you do not know how to proceed with the sowing of the spores may visit

http://amerfernsoc.org/

If the containers are kept closed not need regular watering and less open unless there are risks of infections from mold.

Wandering around the woods, gardens and parks, I noted that it is true that the Harts tongue fers sprout spontaneously in very shady and damp but can grow in places much less humid and shady.
So I wanted to tell Sam that if you have a tree does enough shadow that can be grown in gardens.
The conditions for the spores can germinate and survive young protalli are very different from those in which adults can thrive and a proof are the ferns in my garden, some are born almost on the concrete wall

One in particular gets a lot of sun, the roots dispose of calcium but have very little moisture.

I transplanted the other between the camellias under the fir trees and smothered in ivy, the soil is very acidic and the first 20 "remain dry for more than a month and when the leaves are wilted I water but most of the water it will settle for rains.

I would say that it is a fern very resistant, just plant it in the ground when it is enough strengthened and be careful to water it on a regular basis until it could develop a good root system.

As soon the spores are ready I send them to you.