Those perennial peas you see in fields and on roadsides are mostly another species, L. latifolius. Sometimes, they can be this closely related one, with narrow leaves. In my experience, this is not quite as bright, and more consistent in its color. L. sylvestris has been reported from AR, CO, CT, GA, ID, KY, MA, MI, MN, MS, MT, NC, NH, NY, OR, SC, TN, UT, VA, VT, WA, WI, WV, WY, BC, NB, NS, ON, PE, and QC. Hartwick Pines State Park, Crawford Co MI, 6/30/11.