We've all read those lists of clothing items we should buy at every age—and their less savory counterparts, dictating the items we should definitely not have in our closets by the time we hit a particular decade. But fashion operates in seasons and trends. What about the big stuff? The keepers, that we'll live with for years to come? New trad doyenne Elizabeth Pyne, who heads the youthful McMillen Plus offshoot of her mother's storied design firm, and her colleague Lauren Frasco share the timeless pieces you should be considering now and forever.