Samples from a collection of 50-thousand photographs cataloguing decades of Iowa farming history go on display this weekend at the Governor’s Mansion. Self-described agricultural photographer A-W “Pete” Wettach of Mount Pleasant snapped the images on Iowa farms from the mid-1930s on through about 1960. Though Wettach died in 1976, an archivist says his work will live long in the black-and-white pictures.Leslie Loveless, an editor at the University of Iowa’s Institute for Rural and Environmental Health, is organizing the massive collection. She calls the wealth of five-by-seven-inch photographs a “fantastic historical catalog” of Iowa farm activities and even crops that aren’t seen anymore. About 30 of Wettach’s photos will be on display this weekend at Terrace Hill and next month at the Iowa State Fair. The free exhibit will be open from 10 to 4:30 on Saturday and from 10 to 2:30 on Sunday.