What did the farmers do with the individual ripened stems in the barley harvest?
The farmers took the individual stems that were ripened, made them into a sheaf, and presented that sheaf as the first fruits of the barley crop. This prefigured Christ's resurrection and those who came out of the grave as the first fruits of the spiritual harvest.
Les explains that this is a literal grain harvest, a literal 40-acre field of barley. The workers went in, took the individual stems that were ripened, made their sheaf, and presented it as the first fruits of that crop. He then connects this to Christ, who has been resurrected from the dead, and to those who came out of the grave, who now make up the first fruits of the spiritual. Les also notes the Leviticus 19:9 instructions: when reaping the harvest, they were not to wholly or completely reap the corners of the field or gather the gleanings, but leave them for the poor. After the first fruits were taken out, the main field would be harvested, except for the corners and a few gleanings, separate stems left lying on the ground. That main harvest was probably 98% of the total.