Micro-expressions (MEs) are involuntary facial expressions that reveal genuine emotions and have significant applications in fields such as psychology, security, and human-computer interaction. However, previous ME datasets are mainly collected in controlled laboratory environments, such as fixed views, single illumination and head movements, limited subjects and the lack of background. There are significant gaps between them and the real world. To handle this issue, we introduce a novel Natural Micro-Expression (NaME) dataset, a natural dataset collected under unconstrained real-world conditions. It encompasses (1) diverse subjects, multiple views and varying head movements ; (2) rich background information, providing a more realistic benchmark for the micro-expression recognition (MER) research. Furthermore, we propose a MER benchmark for natural environments, named MixFormer. MixFormer includes an efficient sparse attention mechanism to capture subtle facial motions from various factors, and a face-background mix of attention module to model the environment context to help MER. Extensive experiments are conducted to analyze our NaME dataset and benchmark. We believe that our dataset and benchmark will pave the way for future research in MER beyond controlled settings, facilitating the deployment of MER in practical applications. NaME is available at github.com/real-ljt/NAMEdataset.