I'm also in the black walnut fan club. I like eating them straight, but that may be a by-product of hulling being so time-consuming and messy if done by hand (wear gloves - they stain!), so I usually didn't collect enough to use in a recipe.
To me they taste like summer because one of the towns I grew up in had black walnut taffy as a big thing. I highly suspect there wasn't actual black walnut in most of the taffy sold, but it's a nice idea. Black walnut can be a polarizing flavor though, so try before you plant if you've never had them before and aren't just growing them for shade or for their (excellent, high-value) wood.