By Tim Fall For The Oklahoman trfall@oklahoman.comThese walls could talk. Jim and Lawanda Pickens launched into a massive renovation on the third story of their home at 801 NW 17 — a job that required tearing out a wall or two. When they did, they discovered a box of letters hidden behind the plaster. Their walls not only talked, they told a story — one side of a love story, at least — from a century ago. The letters are undeniably love letters, dating from November and December 1915 — handwritten on stationery from the Skirvin and other hotels in downtown Oklahoma City and around the state. The Pickenses will share what they know of the mystery and the renovation of their Swiss Chalet-style/Craftsman home during the Mesta Park Holiday Home Tour next weekend.