The Wealth of Nations by Part 1 Chapter 11 Page 101

This statute is surely a better evidence of what was reckoned in those times a moderate price of grain than the prices of some particular years which have generally been recorded by historians and other writers on account of their extraordinary dearness or cheapness, and from which, therefore, it is difficult to form any judgment concerning what may have been the ordinary price. There are, besides, other reasons for believing that in the beginning of the fourteenth century, and for some time before, the common price of wheat was not less than four ounces of silver the quarter, and that of other grain in proportion.

In 1309, Ralph de Born, prior of St. Augustine’s, Canterbury, gave a feast upon his installation-day, of which William Thorn has preserved not only the bill of fare but the prices of many particulars.