This keys to Galium binifolium ssp conforme in Ian Thompson's revision paper of Asperula and Galium (Muelleria 2009). In this subsp there is not the marked difference in length between leaves and stipules in each whorl of 4, so binifolium does not immediately suggest itself. Stipules are allowed to be half to 3/4 of leaf length; these are about 3/4. Corolla lobes are about 0.8mm long, and not purple on the outer surface, so it is not G. gaudichaudii ssp parviflorum, which is the other branch in the final lead of the key. I've seen it before in our moist forest, but it is unusually abundant in this wettish spring.