Edit in JSFiddle

$(function() {

getMedia('samphorsc');

function getMedia(username) {
  $('.loading').show();
  $.ajax({
    url: 'https://api.pinterest.com/v3/pidgets/users/'+username+'/pins',
    dataType: 'jsonp',
    type: 'GET',
    success: function(data) {
      $('ul.grid').empty();
      var img = '';
      var html = '';
      for( x in data.data.pins ){
        if ($.isNumeric(x)) {
          $.each( data.data.pins[x].images, function( key, value ) {
            img = value.url;
          });
          html += '<li>';
          html += '<img class="media-Instagram" src="'+img+'"/>';
          // img.replace('237x', '564x')
          html += '</li>';
        }
      }
      $('ul.grid').append(html);
    },
    error: function(data){
      console.log(data);

    }
  });
}
})

<ul class="grid">

</ul>

ul.grid li {
  display : inline;
}

li img {
  width: 120px;
  height: 120px;
}