It does sound like the legume tree, Robinia hispida. It's blooming right
now here in Georgia. Tends to be a smallish tree, to 30 or so feet and
often shrubby in hedgerows. The piniksh flowers droop like black locust
but look a little more like wisteria. The "hispida" part of the name
refers to the many hairs all over the young twigs. It is armed with mean
thorns. Many consider it a weed, but under control it can be very nice.