Laravel Eloquent - how to join a table

I working on an API for my app.

I'm trying to pull items from the database and return them in JSON object, my items table looks like this:

Items
-id
-name
-description
-price
-currency_id
-company_id

this is how I'm getting the items:

$rows = Company::where('guid',$guid)
                ->first()
                ->items()
                ->orderBy('name', $sort_order);

I want to replace the currency_id with a currency object that contains all the columns of currency table

so my result will be like this:

[
  {
    'id':'1',
    'name':'name',
    'description': 'example',
    'price':'100',
    'currency':{
     'id':'1',
     'name':'usd',
     'symbol': '$'
     }
  }
]

update: This is my currencies table:

id
name
symbol
code