This is the blossom of the wineberry, also called the Japanese wineberry or the wine raspberry. A native of China, Japan, and Korea, it was introduced to the U.S. in the 1890s, escaped cultivation, and is actually considered invasive in some parts of the country.
I am happy to be invaded by such a plant. The berries will ripen around the 4th of July, and, if I’m around to pick them, they will decorate my bowl of oatmeal every morning for a week or two. They are delicious. The word “wineberry” describes them accurately.
Collecting them, however, is a sticky business. See those little red hairs? Every one of them holds a tiny glob of an amazingly gluey substance. I have learned that it is a good idea to bring a couple of baby wipes along on a wineberry-picking expedition.