So far I've dug all the Forest, (beside starting location will check it soon), Rat Den and currently checking Spiders Cave.
PS: I'm checking EVERY single tile, so no worries.
Sorry I couldn't answer you before, no, at the moment there are no more places to use the shovel, it's content that I have to implement, but I'm glad you decided to dig everything, xD, that's the intention, but the prize is yet to be implemented, sorry. I've been taking care of making all the main mechanics work and I still have to tweak a couple of things, as soon as everything is okay I will start adding all the missing content.