Wheat like barley, was associiated with the Egyptian cult of Osiris.

The death of a grain crop is followed after a period of stillness, by the re-sowing and germination of the seeds.

Though no corpses have produced new people, headstone masons still employ the ear of wheat as a symbol of rebirth.

Convent bakers use wheat flour to make communion wafers, making it a holy plant, of sorts, fit to grace the grave of a priest.

A Sheaf of Wheat on a tombstone is often use to denote someone who has lived along and fruitful life of more than seventy years.  It is one of the most basic foodstuffs and is thought of as a gift from God, particularly because its origins were unknown.  It denotes immortality and resurection because of its use as a harvested grain.

A sheaf of wheat is a popular Masonic symbol as well.