If you can buy a dividend stock at a cheap valuation, you might not only lock in a high yield, but by buying at a low price, you can also position yourself for a good return down the road. As interest rates come down, these income-generating investments could be in high demand as investors seek out high returns in the equity markets. There may be some extra motivation to buy attractively valued dividend stocks sooner rather than later -- their prices may not stay low for long.

Three stocks that can be excellent sources of recurring income for your portfolio and that you can get at some incredibly attractive discounts right now are AT&T (NYSE: T), JD.com (NASDAQ: JD), and Comcast (NASDAQ: CMCSA). Here's why you'll want to consider loading up on these stocks today.

1. AT&T

Telecom company AT&T offers an attractive, high-yielding payout of 5.1% right now. That's well above the S&P 500 average of 1.3%. Even though the stock is up 30% this year, because of AT&T's depressed valuation in recent years, it's still trading at an incredibly low forward price-to-earnings multiple of 10.

Given the company's more stable financial performance of late (it has posted a profit of at least $2 billion in each of the past four quarters), there could be even more of a rally ahead for what's still a cheap dividend stock in AT&T. The company is selling its stake in DirecTV, which will bring in billions in extra cash for the business while also simplifying its operating model as it exits the costly and highly competitive media business.

AT&T has generated $21 billion in free cash flow over the trailing 12 months and although it may not be a growth machine, it can make for an incredibly strong dividend stock to buy and hold for the long haul.

2. JD.com

Online Chinese retailer JD.com pays a modest but above-average dividend yielding 1.6%. For much of the year, it has been an underwhelming investment as the Chinese economy hasn't been doing as well as investors had hoped. And in its most recent quarter, which ended on June 30, JD.com reported revenue growth of just 1.2%, totaling $40.1 billion.

Lately, however, the stock has been on a tear on news that China's central bank would be lowering interest rates and that the government would deploy other measures to help stimulate the economy. But even with its recent surge in price, shares of JD.com are trading at around 12 times the company's expected future earnings, based on analyst expectations.

A more favorable outlook on the Chinese economy could heighten those expectations and make JD.com's valuation look even more attractive. If you want exposure to Chinese stocks, JD.com can be one of the better options to add to your portfolio right now.