No, I am not up on "treasure trove" laws of CA. It would depend on where you found it too, I suppose. Like if found on private land ( a farmer's field with permission, for instance, or your friend's back-yard, etc...), then that would be totally up to you and the property owner. But if found on any sort of public land, I bet that if you walked in to any entity's headquarters (city, county, or state, depending on which level of land), and if you were to ask the desk-clerk: "hi, I found this box of 1800's gold coins on your [park, freeway median, beach, campground, mountains, lake bottom, etc....], then, doh, what do you THINK they're going to say??