These beautiful (blown) eggs were a gift from my niece Amelia.
She told me she got them at an antique shop and was told they were Brown-headed Cowbird eggs.
For the most part, selling eggs and feathers of wild birds is prohibited but this may not apply to antiques. Also, the Cowbird is a bit of a thug ( see HERE), thoroughly despised by most bird lovers. It may not be protected.
No matter -- the eggs are beautiful..