Poppy seeds are an oilseed which is obtained from the opium poppy. They are tiny kidney-shaped seeds which have been harvested from dried seed pods for thousands of years.
So can gerbils eat poppy seeds?
Unfortunately they are extremely high in fat and very acidic. The problem if they eat foods that are high in fat and acidic is that they will get sick if they eat a lot of them.
So if they have one or two poppy seeds they will be fine. But they are a food to steer clear of feeding them purposely. There are better foods that they will like and enjoy, are better for them.