I've had just a couple of sets of Japanese wooden nesting eggs before and, as with treen apples, also made in Japan and to which they are close kin, I always keep an eye out for them, though they are rarer than apples to find. C. 1920s I believe, with the shells of each egg progressively thinner as they get smaller; rare to find a set of these with all of the eggs in tact! (And indeed, one half of the smallest here was found taped together so I haven't even included it.) The largestis the first I've seen decorated with a hand-drawn butterfly, which is charming, and then the rest in bright pink (I think decorated while spinning) and finally green. 

Six complete eggs here and then a partial seventh. A few small dings to a couple of the smaller ones, as pictured. Largest egg, which is quite lovely, 2 1/2" t x 1 13/16" d.