With the Federal Reserve resuming its rate-cut cycle, now is an ideal time to update our quarterly Where to Invest $10,000 series. Americans are sitting on tons of cash — almost $20 trillion worth, to be exact, including $7 trillion in money market funds. Over the last few years, holding cash has paid off, with money market funds, certificates of deposit, and Treasury bills yielding substantial returns. But now, as the Fed slashes rates again, those low-risk yields are starting to fall, and