Would it be ok to sift the dirt and eat a small amount
Just perennial plants.
Ingesting a small amount of dirt is not dangerous, as long as the dirt does not contain any contaminants or poison like herbicide or pesticide. I don't think it matters if the dirt is sifted or not. However, routinely feeling the desire to eat dirt is probably something one should talk to a physician about. BTW, in gardening circles, "zone" refers to the USDA hardiness zone in which you live. This article tells you more about that: https://www.gardeningknowhow.com/planting-zones/usda-planting-zone-map.htm