The book of Ruth gives us our first proper look at Bethlehem in the Bible. It's mentioned twelve times before this, but never with any detail about what the town was actually like. In Ruth, we're introduced to a farming town busy with the barley and wheat harvests. Both crops are planted in the autumn. Barley matures faster than wheat, so it's harvested in late spring. Wheat is then harvested during early summer.
So Ruth worked alongside the women in Boaz's fields and gathered grain with them until the end of the barley harvest. Then she continued working with them through the wheat harvest in early summer.
— Ruth 2:23 NLT
The story of Ruth gives the impression that Bethlehem is a prosperous farming community. For example, Boaz (who—spoiler alert—ends up marrying Ruth) is described as "wealthy and influential" (see Ruth 2:1), yet his barley field is just one of many (see Ruth 2:8). We're also told that Naomi is selling her husband's land (see Ruth 4:3 & 9), and that another relative was wealthy enough to buy it off her, though perhaps not wealthy enough to support another wife! (See Ruth 4:6).
Both barley and wheat are used to make bread. Indeed, Jesus' feeding of the five thousand uses five loaves of barley bread (John 6:9).