Vivien Straus is unabashedly reflective—especially when it comes to her love life, says Michael Straus, her brother and publicist for her new one-woman play, “E-i-E-i-OY! In Bed with the Farmer’s Daughter,” opening this Friday, April 4 in San Francisco. Ms. Straus, whose father started the dairy that became Straus Family Creamery and whose mother co-founded the Marin Agricultural Land Trust, peppers her play with the wisdom she’s picked up from cows (people have to see…