America has built up a glut of cheese so big that every person in the country would need to eat an extra 3 pounds this year to work it off. And it isn’t just cheese. The growing stacks of cheddar, which can be kept frozen for years, and other cheeses such as feta, which can be stored for only a couple of months, are just the tip of a surplus of U.S. agricultural products that is swamping markets for grains, meat and milk. Supplies of cheese, meat and poultry started building as farmers decided to expand their herds and flocks two years ago when prices were high and export markets were hot. Abundant stockpiles of grain made it less risky by pushing down feed costs. But the steady climb in the dollar has deterred major foreign buyers, causing supplies to back up in the U.S. just as production is surging to records. That is sending prices for many goods to their lowest levels in years. America’s dairy farmers are expected to produce 212.4 billion pounds of milk this year, the most in history. Much of it is being sold to cheesemakers who are socking away their output, waiting for demand and prices to rise. Commercial cold-storage freezers held a record-breaking 1.19 billion pounds of cheese at the end of March, the latest month for which data is available, up 11% from the same time last year.