There’s a difference between fresh produce and commercially processed prodcuts, or cooked dishes from a restaurant. If you’re not the one doing the checking, it’s logical to want someone qualified (a rabbi) to make sure that it gets done. I don’t think that anyone here would assert that you need rabbinical supervision in your own kitchen.

Anyway, here some guidelines for insect checking from the Star-K. (Of course, there are differing opinions on the details.) IANAR, but I would think that the best way to inspect fiddleheads would be the method used for cluster vegetables (broccoli and cauliflower).

As to whether one needs to be a rabbi to properly inspect them, I agree that one does not. HOWEVER, if you have seen previous threads on Kosherblog, you will see that there are those here who think that rabbinic inspection is required (or at least detailed instruction from and continued oversight by a rabbi.)

Of course they’re kosher, they’re plants. It’s the bugs that aren’t kosher, and you don’t need to be a rabbi to check for them.

A few tips on how to get these clean, as they are a royal pain otherwise:
1) Rinse thoroughly.
2) rub fiddlehead in a towel, this loosens the outer layer and hopefully removes it.
3) Blanch the Fiddleheads in a pot of boiling water, TWICE, each time for 2-3 minutes. The second change of water is quite important and eliminates much of the negative earthy (dirt) flavors.

In NYC they are available at Union Square greenmarket, for about 3-4 bucks per pint container.

A woman selling them at Greenmarket told me that she serves Fiddleheads sauteed in breadcrumbs, and her kids love it. Persoanlly, I like to sautee them in olive oil (or butter) with garlic, or ramps. Ramps are in season in early spring, as well.