Most pickle recipes that want extra crunch call for a grape leaf in the jar. Grape leaves are full of tannins, and tannins are what keep the enzymes that make pickles go soft from doing their thing. It's a real trick, not just an old wives' tale.
Problem is, I don't have a grape vine. Not yet, anyway — that's a someday project, still just a line item in my head and nowhere near the dirt.
What I do have is an oak tree in my own yard, and it turns out oak leaves carry plenty of their own tannins too. Same trick, different tree. So I rinsed a few leaves off, laid them out to dry, and tucked them right into the jars alongside the cucumbers.
I like this kind of substitution more than I probably should. It's not a compromise, exactly — it's just using what's actually growing around you instead of waiting on what the recipe assumes you have. The grape vine will happen eventually. Until then, the oak tree's more than willing to help.