minecraft-assets/data/minecraft/recipes/gray_bed.json

{
  "type": "crafting_shaped",
  "group": "bed",
  "pattern": [
    "###",
    "XXX"
  ],
  "key": {
    "#": {
      "item": "minecraft:gray_wool"
    },
    "X": {
      "tag": "minecraft:planks"
    }
  },
  "result": {
    "item": "minecraft:gray_bed"
  }
}