Many blue-chip dividend stocks are widely known and commonly covered, but for every well-known dividend stock, there are a few unknown gems. These underappreciated stocks can be just as big a home run as their more famous blue-chip counterparts, and three Motley Fool contributors think you should check out Cal-Maine Foods (NASDAQ: CALM), Aptiv (NYSE: APTV), and S&P Global (NYSE: SPGI). Not your usual dividend Jeremy Bowman (Cal-Maine Foods): On first glance, Cal-Maine's dividend doesn't look like anything special at a yield of just 1.4%. However, the egg producer's dividend policy differs from most companies. Rather than pay a steady dividend and raise it modestly every year, the nation's largest egg producer calculates its quarterly dividend as a third of its net income in the previous quarter. Over the last five years, Cal-Maine's dividend yield has fluctuated from zero to more than 6%, where it spiked in 2016 when egg prices rose due to the avian flu epidemic. However, in the quarters following that, the company did not have a profit or pay a dividend as egg prices crashed. In the near term, the stock's trajectory will continue to be governed by price volatility in the egg market. But over the longer term, several factors favor the company. First, consumption of higher-priced specialty eggs that are cage-free, organic, or free-range is growing quickly, taking share from conventional eggs. In its most recent quarterly report, Cal-Maine said that revenue from specialty eggs increased to 35% of its total, from 30.2%, a trend that should drive increasing revenue. Second, per-capita egg consumption is near all-time highs and growing. Eggs are a high-protein food with no direct substitute, and the food has withstood faddish diets like the low-carb regimen. Third, California passed Proposition 12 last year, requiring space minimums for hens starting next year and that all eggs sold in the state must be from cage-free hens by 2022, which should spur the transition to specialty eggs. Cal-Maine has invested in new plants accordingly, which should eventually pay off as the California law lifts prices. Finally, Cal-Maine should offer investors stability even if a recession hits, as eggs have fewer substitutes and price changes don't affect demand as much. Cal-Maine's dividend will continue to be volatile, but for investors willing accept its unpredictability, the stock could pay off in multiple ways over the next few years. Triple zero Daniel Miller (Aptiv): The automotive industry as we know it is poised to change rapidly over the coming decades. The industry is heading toward a future with zero emissions, zero congestion, and zero crashes thanks in large part to electric vehicles (EVs), smart mobility, and driverless cars. The development of driverless technology makes Aptiv an amazing long-term stock (more on this in a second), and many don't realize that it already pays a dividend for investors willing to wait for that future, even if the dividend doesn't show up on most stock screens. Image source: Getty Images. Aptiv isn't yet a household name, but the company is an industry leader in vehicle architecture and essentially provides the brain and nervous system of the EV. Along with vehicle architecture solutions, the company has a portfolio of technologies that will focus on making a safer, greener, and more connected automotive industry. The driverless vehicle future may be decades away, but Aptiv is moving ahead already, even announcing the expansion of its autonomous capabilities with its new China Autonomous Mobility Center just a little over a week ago. It's a strategic move, as many anticipate that the Chinese market will become the global hub of EV fleet development as well as driverless vehicle technology. There are key catalysts and megatrends that could propel Aptiv's share price in the years ahead. Consider that Active Safety, vehicle electrification, and vehicle connectivity markets are expected to grow at compound annual growth rates (CAGR) of 15%, 20%, and 17%, respectively, through 2025, according to company estimates. Aptiv plans to spend between 45% and 55% of its capital deployment on mergers and acquisitions to boost its foothold in the expanding industry, but it also notes that spending 10% to 15% on maintaining and increasing a competitive dividend is a priority. And while Aptiv remains an unknown dividend stock because its yield is a modest 1.1% currently -- which won't show up for many dividend stock screens -- it could be an amazing long-term play as the automotive industry evolves into a future dependent on technologies it is is developing. Hidden in plain sight Jordan Wathen (S&P Global): Many investors reference one of its key products every day (the S&P 500 index), but given that shares are owned almost exclusively by institutions, few individual investors seem to know of S&P Global's existence as a public company. S&P Global makes its money providing data and research on large public and private companies. Its biggest and most profitable unit is its ratings business, which earns money providing credit ratings to corporate borrowers and bond issuers. When a company wants to borrow money, it must get a credit rating to borrow on favorable terms, typically choosing to pay one or two of the big three credit rating agencies (S&P, Moody's, and Fitch) for the service. Ratings agencies aren't eager to compete on cost, since only three companies effectively control the entirety of the industry, leading to massive operating margins in excess of 50%. S&P Global's fast-growing indices business also shows a lot of promise. This business line makes money primarily by licensing the company's indices (such as the S&P 500) to index funds, typically assessing an annual fee on every dollar held in a fund bearing one of its indice's names. As investors increasingly allocate their money toward passive index funds, S&P Global benefits in the form of higher licensing fees. This business is best described as a royalty on the growing assets of passive funds. Though S&P may offer a current yield of only about 1%, one should expect that dividend to grow at a rate well in excess of the market average as the company uses virtually all its earnings power for dividends and buying back stock. A single-digit increase in corporate debt issuance and inflows into index funds over time should lead to similarly sized increases in net income and free cash flow, enabling the company to afford double-digit dividend increases for a long time to come. 10 stocks we like better than S&P GlobalWhen investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has quadrupled the market.* David and Tom just revealed what they believe are the ten best stocks for investors to buy right now... and S&P Global wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of March 1, 2019Daniel Miller has no position in any of the stocks mentioned. Jeremy Bowman has no position in any of the stocks mentioned. Jordan Wathen has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Moody's. The Motley Fool has a disclosure policy.Source