Gathering means collecting plants that grow wild for food. Early humans gathered all of their food from the land around them. Men and women and children moved from one place to another: in February, in West Asia, they might be gathering wild greens like parsley, mint, or onions. In April, they climbed trees and cliffs to get bird eggs from their nests. In May, children searched for wild strawberries, and in June they harvested wild barley and wheat and millet and lentils and chickpeas. In July they cut hay to make hats and sandals and sleeping mats. Later in the summer they picked figs and apples, and in the fall it was mushrooms and almonds and walnuts from trees. In November, it was time for the olive harvest. In each season, they ate some of what they gathered, and stored some for other seasons by drying it or smoking it or pickling it. People also got food from hunting and fishing, but most of what they ate came from gathering.
Until around 8000 BC gathering was the main source of food. Around 10,000 BC, in the New Stone Age, people began farming, and therefore spent less time gathering. Now they grew grain instead of gathering it. People soon also began to grow parsnips and peas and figs and lentils.
But they kept on picking many other wild foods. They picked berries, apples, pears, olives, and nuts. They gathered snails from bushes. By the Bronze Age, around 3000 BC, people planted more kinds of food and gathered less. Bronze Age people planted grain and vegetables, but they also planted fruit trees and olive trees. Still, they picked nuts, mushrooms, herbs, and berries in the wild.
In fact, the situation has not changed much from then until now. Even today, many people still gather their berries and nuts, and some people still gather mushrooms and herbs.
It might seem like gathering is a rather lazy, disorganized sort of way to get food, and doesn't need much knowledge. But really it is very complex. You have to know where the plants are, like where are the nut trees growing and where are the berry bushes. You have to keep track of when each of them will come ripe, so you don't accidentally miss all the berries by not visiting their bushes the right week. You have to arrange things so that you are in the right place at the right time.
Then also, once you have picked the food you have to preserve it and store it: you have to thresh the grain, and dry the berries and fruit and herbs, and pickle the olives. Usually people who get most of their food from gathering have a regular route that they travel around every year, designed so that they are at the nut trees when the nuts get ripe, and at the olives when the olives get ripe.
But even with all this, studies of gatherers suggest that most gatherers only really work at gathering food for a few hours a day, much less than farmers work. That is, people began farming not because it was easier, but because it could feed more people on smaller patches of land, when climate change made some land into deserts where nobody could live.
Learn by Doing - Go Berry Picking!
The Cambridge Encyclopedia of Hunters and Gatherers, edited by Richard Lee and Richard Daly (1999).By specialists, but accessible to interested adult readers.
Woman the Gatherer, by Frances Dahlberg (1983). A collection of essays.
Neanderthals, Bandits and Farmers: How Agriculture Really Began, by Colin Tudge (1999). An attempt to explain why people gave up gathering and began farming. Short, and not too hard to read.
Last Hunters-First Farmers: New Perspectives on the Prehistoric Transition to Agriculture, by T. Douglas Price (1995). A more academic book on the same problem.