They are also known as Russian nesting dolls or Babuska dolls. I don't remember when I first encountered one in person, but I know I've seen many over the course of the 20+ years that I lived in Alaska.
There is something so mysterious about them. Don't you just feel compelled to open them to see what's inside? How many are in there? Are they all alike? What will the smallest one look like? ... etc.
My recent series of Matryoshka doll engravings combine both my love of nature and these mysterious little dolls. I have found illustrating these to be quite addictive — the possibilities are infinite!
Individual prints of these are now available on my etsy site.