Overriding default block drop behavior

I'm learning datapacks, and I'm starting out by just trying to alter the dropped item from dirt blocks. I have a mod that I'm building, and I'm unclear if I need to have a file in data/minecraft/loot_table/blocks/dirt.json or data/mymod/loot_table/blocks/dirt.json
I was attempting to just simply change the drop from dirt to be stone instead of dirt as a sanity check. I have modified both mymod dirt.json and minecraft dirt.json, but both are not changing the drop of dirt. Any help would be greatly appreciated!
Here's my dirt.json and my pack.mcmeta has pack_format as 15 (I'm on 1.20.1)
{
  "pools": [
    {
      "rolls": 1,
      "entries": [
        {
          "type": "minecraft:item",
          "name": "minecraft:stone"
        }
      ]
    }
  ]
}