Home Meal Planner - Kids
A fun booklet on cooking and... well, meal planning. The publishing date says 1957. No mention of who the illustrator is, of course.
Using a watermelon in this illo is a good choice because both kids can share the object, plus it's cool to draw a watermelon slice in this style.
UPDATE: Illustrator pal Steve Lambe informed me that the artist is Albert Aquino. Thanks, Steve!