Bill's Botanical Forays

Which species of Oxalis is this? I suspect it could be Oxalic colorea? Maybe. If not what other species could this be? We have measured the petals to be at least 7 mm, but never more than 10 mm. It was first found on the Patuxent Research Refuge, Maryland in April 2017. These images were taken on 18 May 2019. Please scroll down to see all the images presented here. More images can be easily taken if necessary. Physical herbarium vouchers of the sighting will also be available later.