In the mid-1950s I had a book about two children learning about nature from their grandfather(?). Probably an elementary textbook from the 1930s (I had a second book at the same time: “Following the Frontier” by W. L. Nida, 1934, so the book in question probably came from the same school discards). The book in question had ink line drawings — I remember a drawing of a potter wasp or mud dauber wasps’ nest shaped like a vase.
Could this possibly be ‘Enid Blyton’s Nature Lovers’ Book’ (1941)?. Children learning about nature, not from their grandfather but from a neighbour whom they call ‘Uncle Merry’.
Possibly Enid Blyton’s “Nature Lover’s Book” ? It has been reprinted.
From Goodreads: ” First published in 1944, this delightful collection of stories, poems, and nature facts is centered on three children and their uncle who takes them on nature walks, unveiling the delights of the countryside throughout the seasons.”
Further to my previous comment, I want to add that the book I’m referring to is “Nature Lover’s Book No. 2: Country Walks with Uncle Merry.”