In vegetables there are very few varieties which are more than 100 years old. Plant breed programs have improved yields and disease resistance (often at the expense of flavour and nutritional value) beyond all recognition. Fruit trees, probably because of the time required to bring a new variety to the market are a different matter. If you would like to eat a piece of agricultural history then Doyenne Du Comice is a fine place to start. This pear was bred in France in 1849, just 30 or so years after the death of Napoleon and a year after the February revolution forced King Louis-Phillipe to abdicate and flee to England. It was introduced to England by Sir Francis Dyke Acland in 1858. It is still in commercial production in the continent.
I remember watching a gardening program in the 80’s where the presenter was emphasising the speed at which you needed to cook sweetcorn from the moment it was picked as the sugars started to turn to starch. In those days the only way to taste good sweet corn was to grow your own. Sweetcorn breeding has come a long way since then with the development of the tender sweet and then super sweet varieties, both of which are much sweeter and also have a longer shelf life which means no more running from plot to plate!