What is are augenblicks and how what does Dillard do with them?

An "augenblick" is a brief glimpse of the present moment. When Dillard states that she collects these augenblicks, she means that she tries to remember snapshots of significant moments. For example, when she sights a muskrat paddling on its back in Tinker Creek, it is an augenblick, which she stores in her memory.