Since taking over Berkshire Hathaway in 1965, Warren Buffett has delivered phenomenal returns for investors. For example, if you invested $100 in Berkshire Hathaway in 1965, it would be worth more than $2.4 million today. Two intriguing Buffett stocks to buy hand over fist in March are American Express (NYSE: AXP) and Markel (NYSE: MKL).