Wal-Mart Stores have recalled a house brand of trail mix after three customers said they found glass or hard plastic in bags bought in North Carolina and Ohio. The retailer says it has taken remaining bags off shelves nationwide. Wal-Mart said it ordered stores over the weekend to remove Sam's Choice "Nature Trail" Trail Mix from sale. A Wal-Mart spokeswoman says the stores also programed cash registers at all stores to block sales of the product. The company that makes the mix says it has launched an investigation at its plant in Robersonville, North Carolina, where the trail mix was produced.