Olives have been on the table for about 35 centuries. Your standard olive is inedible when first harvested in that it contains a large amount of acrid glucosides which are horrendously bitter. To remove this, olives are soaked for a few days in lye (doubtless produced from wood ashes, which added a bit of the flavour of the particular wood). Then they were soaked in brine and finally approached edibility. How they got those little pimento things in the middle is yet to be discovered.