Mint and sage both give off scent. I wonder if they were placed there for that reason?
Also both have been used in a metaphysical way.
Mint is a near-essential herb for your cabinet because of its powerful healing ability. For healing spells and prosperity in all forms, mint is a desirable base.
Sage is used in magic for wisdom, psychic awareness, long life and protection.
Could be this was for protection and healing in their next life.
Especially in mint juleps. ;-)
Aromatic herbs cover or alter the stench of decomposition; use of them in a burial suggest those doing the burying were familiar with this, iow, had buried their dead before. For that matter, they may have needed to do this because they continued to live at the site, a practice found in Sumerian sites from thousands of years later.