Forsythia flowers in the early spring, grows in the sun and the leaves turn bronze-red in the fall. Mahonia has holly-like leaves, grows in the shade and bright yellow flower clusters in late winter, early spring. Its foliage stays green all winter. There are many varieties of mahonia with different mature sizes. Hypericum has yellow flowers and some have showy fruit. Potentilla has small green leaves and yellow or white flowers. It is a tough plant with a small, mature size. Both hypericum and potentilla work well in mixed borders with perennials. I hope this helps with your plant I.D.