Thomas Merigan <www.stanford.edu/~merigan>, in his database of plants of Jasper Ridge, distinguishes Fat Solomon's Seal (Smilicina racemosa) from Slim (S. stellata). This looks more like "Fat". Wikipedia has False Solomon's Seal (Maianthemum racemocum), which looks similar, though a little smaller and without the jagged stem. Fat ID confirmed by Toni Corelli.