Describe the relation between Jethro and his mother in Across Five Aprils.

Jethro has an excellent relationship with his mother Ellen. In fact, she's more like a big sister than a mom. It's a testament to the closeness of their relationship that Jethro and Ellen often joke around together.
At the start of the book, when he's out working in the potato fields with his mom, Jethro teasingly calls Ellen "Ms. Creighton," imitating how his older brothers used to call her when they were playing around. Jethro knows not to go too far and call his mother by her Christian name. This indicates that, joking aside, he deeply respects as well as loves his mom.
That this happy scene takes place right at the start of the book is crucial as it immediately establishes what kind of relationship Jethro has with this mother as well as telling us a lot about their respective characters.