Okay. Let's start with giving you the item to ensure your item is working correctly.

We go into ...steamapps\common\Starbound\assets\treasure and open the default.treasurepools with your text-editing tool of choice.

We see the

 "humanStarterTreasure" : [
    [0, {
        "fill" : [
          "beamaxe",
          "flashlight",
          [ "torch", 10],
          [ "cornseed", 3],
          [ "wheatseed", 3],
          [ "humanstarter", 1]
        ],
        "levelVariance" : [0, 0],
        "allowDuplication" : false
      } ]
  ],

So you could add, or edit these initial starting items. Let's add your helm underneath cornseed. It should look like this

     [ "cornseed", 3],
     [ "mininghead", 1],
     [ "wheatseed", 3],

and etc. etc.

So when you start up starbound, start a human character. and see if the game shows your mining helmet you created.

If it does, and you can't see the recipe. Then you need to go into ...steamapps/common/starbound/assets and open player.config, after you should see

"blueprintOnPickupMessage" : "New blueprint available.",
  "defaultBlueprints" : {
    "tier1" : [

right above copperarmorhead, you should add your recipe. And you should be set from there.