weet Williams or Wild Blue Phlox are blooming in the woodlands now. The purpley-blue flowers grow in small bouquets under the trees. They need rich soil to grow in. The flowers shown at the left are wild but there are several hybrid garden varieties. Sweet Williams are said to represent gallantry.
The closest thing I could find to a reason behind the name was a story about a Scottish lass; Janet, the daughter of Lord Lundy. Her Sweet William went off on a journey. In the meantime Lord Lundy discovered the budding romance and did not approve. Lord Lundy ordered Janet to marry another; but, just in time to pre-empt the wedding, Sweet William gallantly shows up and weds Sweet Janet.
Sources: Audubon Field Guide to Wildflowers; Wikipedia