I love the photo of your grandparents. Kind of reminds me of my own.
I think I remember eating those marshmallow eggs when I was a child. A hard colorful shell, and marshmallow inside that was pretty solid, more hard than marshmallows today.
In our house the eggs to get are the tiny Cadbury pastel chocolate filled eggs. We call them crack eggs because they are horribly addicting.
I think the eggs were Brach's, not sure, and a little over an inch long, proportioned more narrow than a real egg. I got myself some just a couple Easters ago, sure enjoyed them. I also loved those nougat-like ones, ah couldn't think how to describe the shape so looked for something - rectangulaar prism or long little box. They had little chunks of colored they say jelly bean but much chewier, wrapped in clear cellophane. They still have those with not as many colors and in the shape of taffy and wrapped in clear papers twisted.
Wow, four 7-oz bags/package at one place 2# for $24.39. Same amount individually wrapped same price. That's expensive! At the Vermont Store 7-oz. bags for $14.90, about the same.
I will look for the Cadbury eggs you described. I always looked forward to getting the chocolate ones with the white, creamy filling, and I think it had yellow centers for yolks. Their chocolate has always been superb.
I think I found some small Cadbury ones liike you describe at Target with chocolate. There are some Cadbury caramel ones called robin eggs, all like aqua with darker flecks. Yours the photo would be harder or impossible to embed.