Its funny, I talk about biomimicry a lot when I train teachers and work with kids, and to date I have not posted a resource that is super helpful.
So here it is: Ask Nature. This is a fantastic resource if you are looking for inspiration from nature. The site is organized around different structures and functions, and once you start digging into the content you can definitely get lost in the rabbit hole. Lots of great ideas for professionals and kids (most likely middle and high school ages). I have done biomimicry projects with a variety of age levels from 3rd graders to aerospace engineers. It is a great context to take on a new perspective in design and the outcomes are often very creative.