Why can't you go to a garden store and buy fern seeds? answer fast please!
That's an easy one they don't exist. Ferns reproduce via spores and have neither seeds nor flowers.
I believe ferns only grow in certain environments that are humid and moist
Ferns do not have seeds they have spore, you can read all about them on Wikipedia.
Ferns reproduce through spores like that of a mushroom. Therefore, you can't get seeds because there's no seeds, just spores.
You may be able to get fern rhizomes to start your own plants, but its easier to just get an already started plant.