If you buy lettuce leaves in a clamshell or sealed bag, just refrigerate it — but consume it by the use-by date on the package, as bacteria can develop even when the leaves still look healthy. Heads of leaf lettuce and loose assortments of leaves (like mesclun mixes from the farmers market)) should be washed and dried very thoroughly, then stored in the refrigerator in a vented paper bag with a piece or two of paper towel. Head lettuce, like iceberg, can simply be refrigerated in the crisper drawer.
Mushrooms sold in plastic-wrapped cartons can simply be refrigerated as is, and lightly washed or wiped off with a damp paper towel just before using. Loose mushrooms, especially wild varieties, are best stored in vented paper bags in the crisper drawer, and also lightly washed pre-use.
If your peaches are ripe, refrigerate them in an uncovered bowl. To ripen them, put them into a closed paper bag for a few days at room temperature, then refrigerate them in a bowl, uncovered, when they’ve ripened.
If you buy sugar snaps, snow peas, or shucked English peas in bags, simply store them in the refrigerator until you’re ready to cook them. Unshucked English peas or sugar snaps or snow peas you buy loose should be refrigerated in a vented paper or plastic bags.
Treat pears like peaches: If they need to ripen, close them inside a paper bag and let them sit for a few days at room temperature, then refrigerated in an uncovered bowl.