I don't know what this blossom is (I guess we can call it that!). I saw it on a walk in a county park. It was on a bush growing wild there. I think it is intriguing and beautiful in its own way. Can you help ID it?

Ah thanks to Jeanne and to Rick, who both referred to the rose. Jeanne suggested I google 'mossy rose gall wasp' and sure enough I learned that this is a blight caused by two types of wasps. Wikipedia says, "Diplolepis rosae is a hymenopteran gall wasp which causes a gall known as the rose bedeguar gall, Robin's pincushion, or moss gall. The gall develops as a chemically induced distortion of an unopened leaf axillary or terminal bud, mostly on field rose or dog rose shrubs." Mystery solved, but sorry to say it isn't natural beauty. I still think it is pretty.