Texture wise, I find them to be very similar to a curled up haricot vert, or a very young, tender green bean.
By the time the brown stuff (that the above poster talks about) is brown, they’re really too developed. You can still eat them, and they are harmless, but it’s best to get them before these fern bits turn. They are still green and tender for about two weeks.
Because of their popularity, people tend to keep them on menus for weeks longer than they should.
Sautee with butter, splash with red wine vinegar and drink rosé with.