Around the end of summer, some of the pods near the bottom of the stem (the first flowers that opened), may begin to show signs of ripeness. When ripe, the pods begin to split from the blossom end. Don’t worry if this doesn’t happen in the field. Before cold, wet weather arrives, cut the stems at the base and gather them to dry some place that is flat — hanging them will cause the seeds to just fall out as the pods dry. As the plants dry, the foliage will darken and more pods will open from the base of the stem upwards. Once most of the pods have opened, bash them against the sides of a bucket to collect the dry seeds. The seeds are edible at this stage, and resist spoilage better than most nuts. They can also be toasted, pressed for oil, or ground into the paste known as tahini.
Sesame plants each produce quite a lot of seeds, but the seeds have little mass. From a 10 foot long, 2½ foot wide row, expect to harvest approximately 425g (just under one pound) of seeds.