They are all cereal crops. Cereal crops are all from the grass family. a cereal we eat is any grain from any cereal plant, that is usually eaten with milk, but it does not have to be eaten with milk.

I call them grains. Cereals get the gist across, but make me think of the kinds of grains you eat with milk.

Cereal is the bit we eat from grains. It's usually only used to refer to the breakfast cereals you eat in the morning regardless of their content. They can be wheat, rice, oat, it doesn't matter.

Poeple usually say 'grains', I think.