Did you use the word "glean" before you knew its original, agricultural definition? If you paid attention in Art History class, you've probably seen Jean-François Millet's "The Gleaners" painting. The sight of peasants performing the task reinforces that "to glean" means to extract leftover grain following a harvest.
Another word with agricultural roots is "winnow," as in "The prototype helped us winnow out some problems." The word is related to another agricultural phrase, "separating the wheat from the chaff," because that's what winnowing does—using the wind. In pre-industrial farming, wheat is cut from the stalk; then it's threshed (beaten), which releases the grain, along with the useless chaff or husks; and finally it's winnowed—shoveled upwards into the air, or dropped from a height, in a strong breeze. The heavier grain falls straight down while the chaff is blown away by the wind.
Here's a visual example, in this case separating beans from dirt: