[Raided (with permission), the gardener-gatherer-hunter’s garden for peas, picking about a quart of pods…which produced a bit more than a half-cup of peas.]
I noticed that pods in this sample tended to contain nine peas, sometimes ten, once eleven, and sometimes eight…and, if they didn’t all make, fewer. Since they’re attached to the sides of the pod alternately, there tended to be four on one side, and five on the other. I did not examine further to see if it tended to be the same side.
Note that fresh peas, as opposed to machine processed, have that extra bit of tissue attached, the bit that joins them to the pod.