For these projects, I used Avery brand Dark T-shirt Transfers that I found at a craft store. They are meant to be used on dark colored shirts, but I had them left over from a different project and they work just as well on white shirts. Make sure you wash your t-shirt or onesie before applying the iron-on.
this one has a favorite photo of our pet rabbit, Buns. Yes, that is a crown on her head. She was not pleased.
P.S. Thank you, thank you, thank you for all of your sweet comments and well wishes on the last post! I was floored.