Matilda is an elephant who has motherly instinct to sit on an egg until it hatches. This is an early Dr Seuss story for Judge Magazine published in 1938 called Matilda, the Elephant with a Mother Complex.
The story was never renewed therefore it’s another Dr Seuss story that’s in the public domain.
The story itself would be reworked into the Horton book “Horton in Horton Hatches the Egg”, making Matilda like a proto-Horton.
Horton won’t be public domain until 2036 but Matilda already is.