For many American children of the ’80s and ’90s, rice cakes — stacked in a column and kept in long plastic bags — were an omnipresent feature of home kitchens, preschools, and afterschool programs. I can’t remember the first time I held one, but I also can’t remember a time before I did. Palm-sized disks, they’re the same weight as styrofoam with a scant sprinkle of flavor crystals, salt or maybe cinnamon, dusting the top and coating the crevices between