Parcel post is kind of like first class just a slower ground service mail. I use it a lot to send big and heavy packages. You just have to request it and you can even print parcel post from the shipnow in paypalAnything 14 ounce or over automatically goes Priority, not First Class. Your experiment would require shipments of only a few eggs at a time to stay within the weight threshhold. I am not familiar with parcel though . . . what are the requirments for shipping parcel post?