This Google Script will fetch and parse any XML feed and inserts the items as rows in a Google Spreadsheet in reverse chronological order.

Internally, script uses the UrlFetchApp service of Apps Script to fetch the content of the raw XML feed and parses it using the built-in XMLService service. Since spreadsheet data can be externally published as CSV and other formats, this can be extended to convert your RSS feeds into other formats though Google Sheets.

function parseXML() {
  var url = 'http://feeds.labnol.org/labnol';
  fetchFeed(url);
}

function fetchFeed(url) {
  var ss = SpreadsheetApp.getActiveSheet();

  var property = PropertiesService.getDocumentProperties();
  var last_update = property.getProperty('last_update');
  last_update = last_update === null ? 0 : parseFloat(last_update);

  var feed = UrlFetchApp.fetch(url).getContentText();
  var items = getItems(feed);
  var i = items.length - 1;
  while (i > -1) {
    var item = items[i--];
    var date = new Date(item.getChildText('pubDate'));
    if (date.getTime() > last_update) {
      insertRow(item, sheet);
    }
  }
  property.setProperty('last_update', date.getTime());
}

function getItems(feed) {
  var doc = XmlService.parse(feed);
  var root = doc.getRootElement();
  var channel = root.getChild('channel');
  var items = channel.getChildren('item');
  return items;
}

function insertRow(item, sheet) {
  var title = item.getChildText('title');
  var url = item.getChildText('link');
  var author = item.getChildText('author');
  var date = new Date(item.getChildText('pubDate'));
  sheet.insertRowBefore(2);
  sheet.getRange('B2:E2').setValues([[title, url, author, date.toLocaleString()]]);
}