minecraft-assets/data/minecraft/worldgen/configured_feature/pile_pumpkin.json

{
  "type": "minecraft:block_pile",
  "config": {
    "state_provider": {
      "type": "minecraft:weighted_state_provider",
      "entries": [
        {
          "data": {
            "Name": "minecraft:pumpkin"
          },
          "weight": 19
        },
        {
          "data": {
            "Name": "minecraft:jack_o_lantern",
            "Properties": {
              "facing": "north"
            }
          },
          "weight": 1
        }
      ]
    }
  }
}