Wheat is the grain most mentioned in the Bible and is still used in the 21st century.
Grains---the edible seeds of grasses---were some of the first plants to be cultivated by humans. Grains mentioned in the Bible are still grown and used in the 21st century, but English translators also substituted references to grains grown and used in England much later. Some of these plants won't even grow in the ecology of Israel and weren't cultivated anywhere at the time depicted in the Bible.
Basic Wheat
By the 21st century, more than 30,000 varieties of wheat are grown around the world. They have different characteristics, such as how hard it is to get the grains out of the seed heads. Wheat is more useful if it requires threshing rather than dropping grains spontaneously before the full head is harvested. Because the Bible includes many references to threshing wheat, it is likely that the biblical grain is from at least the second stage of wheat's agricultural evolution, emmer. Quite advanced "bread wheat" was grown by the time of the Greek Testament, however.
Other Wheat Forms and Uses
What's known in the 21st century as spelt, a species of wheat, is mentioned three times in the Hebrew Bible, but in the 17th century King James version, the word is translated "rie" twice and "fitches" once. The "parched" grain mentioned in six places, including Ruth 2:14, may also be wheat. The grain is not specified in the Hebrew, however. The King James version infers the English word "corn" (also for 13 other Hebrew and three Greek words), a grain that does not grow in Israel and was unknown there in any biblical period.
Barley
Wild barley still grows in the Middle East and was widely cultivated by Bible times. This grain figures in the Bible as a promise of God (Deuteronomy 8:8) and a tool of war (Exodus 9:31; 2Samuel 14:30). When Jesus is said to have fed the 5,000, it was with bread made from barley flour (John 6:1-13). It's one of five seeds the prophet Ezekiel (4:9) is instructed by God to gather to make bread to sustain himself through a yearlong vicarious siege of Jerusalem. This recipe has been adopted by the company Food for Life for its commercial grain products, though those products add soybeans, another stranger to the Bible.
Millet or Sorghum
Although it was another component of Ezekiel's bread, ground millet contains no gluten and therefore will not rise with yeast. Perhaps it was meant to be kept as small, hard seeds, as it is today included in some breads and also fed to birds and other animals. Millet is a reliable crop, known in a number of species that go dormant in drought and come back when rains return. The mature seeds also keep well, especially unthreshed. Ezekiel's millet might have been the same plant known as sorghum, grown in several places in the modern Middle East but not so much as a food crop.
Grain-Like, But Not Grains
Lentils are used in many of the same ways as grains, including in Ezekiel's recipe and in the stew or "pottage" the patriarch Jacob served to his brother Esau in Genesis 25, but they are legumes, growing in pods. They are often used dried and can be ground into flour. The seeds of the carob tree, another legume, were used in Bible times as a measure of weight because both the beans and the pods are of uniform size. Although carob trees were and are common in Israel, they are mentioned in the Bible only in Luke 15:16.
Tags: 21st century, mentioned Bible, Bible still, Bible times, grown used, James version