In zone 8 Cyprus papyrus, will die back to some degree each winter depending on temperature. But it always comes back vigorously and is invasive here. Acorus is a more cold hardy bog plant . It is very easy ( aka invasive) here; if you want something to try. Acorus is often variegated color and gets about one foot tall.
I'm going to guess (by the look of the seeds and pictures I see online) that it's either sorghum or sugarcane, since the seeds look similar to those, and corn. If not, it's probably a relative of them (in the Poaceae family).
I've grown sorghum before. Mine had round seeds, but I see pictures of sorghum seeds that look more of a corn shape, and are the color ...
I have a hunch that it could be a sapodilla seed, though I have no idea whether they smell like almonds or taste like mints. If you could provide a picture of this thing before cracking then it could indicate if it follows the pattern of a sapodilla seeds.
However, check the images of these seeds. I found they are similar.
The closest match I saw on Pl@ntNet would be Terminalia catappa. Unfortunately, with just a single photo of the exterior of the seed, it's difficult to confirm. But it's consistent with your description that is smells like almond (indeed, one of the common names is "Indian almond"), and that there's just a single seed inside the pod.
On the latter ...