It would first be useful for doanting to th shrines, like the other gems, but i think it would be cool if you could also melt it in your mouth or something (It's just hardened syrup yeah?) and find weird ancient glitch-bugs or other weird stuff lol
fwiw, I dug up a turn of the century porcelain button and a small bit of gold plated jewerly (broken tiara I think) while gardening irl, so it's no unrealistic by any means.
It would be kinda cool if there were some items you could only get by digging up a patch. Then, of course, everyone would be digging up patches, so maybe not.