Were bread and wine ever combined in Old Testament worship?
No. Throughout the Old Testament economy, bread and wine were never associated in combination. Bread appeared in tabernacle worship, such as the table of showbread and the wave offering of grain, while wine was used separately in drink offerings. Their combination points forward to the Lord's Supper in the age of grace.
Les explains that in the middle of verse 18, Melchizedek brought Abram bread and wine. But this was not a pattern for Old Testament worship. He notes that bread was used in tabernacle worship, including the table of showbread, and the wave offering was a sheaf of grain. Wine was used separately as drink offerings that were poured out. Les emphasizes that never were bread and wine associated in combination throughout the Old Testament economy. For the age of grace, bread and wine speak of the Lord's Supper, the communion table, which he connects to Matthew's account of the Lord's Supper.