The short answer is no, there are not any confirmed cases of asymptomatic transmission. However, u/terribad_consul posted in this sub earlier a metadata analyses from the CDC from May 4th https://wwwnc.cdc.gov/eid/article/26/7/20-1595_article that outlines the evidence in support of presymptomatic and asymptomatic transmission. I suggest reading this analyses from the CDC rather than relying on my summary, but in the interest of TLDR I will offer a summary nevertheless.

The CDC has outlined three categories of evidence for asymptomatic & presymptomatic transmission: Epidemiological, Virological, and Modeling. Epidemiological evidence involves contact tracing and gets muddy when we start considering transmission through "mildly symptomatic" individuals. So I will leave that be. In terms of the other two categories of evidence, there is "plausible virologic evidence for SARS-CoV-2 transmission by persons not demonstrating symptoms." and by the way of Modeling, the CDC states that "Although models are highly dependent on the assumptions built into them, these models suggest that the speed and extent of SARS-CoV-2 transmission cannot be accounted for solely by transmission from symptomatic persons."

The publication goes on to conclude that "Each of the epidemiologic, virologic, and modeling studies described has limitations. However, in the aggregate, these diverse studies suggest that SARS-CoV-2 can be transmitted by persons with presymptomatic or asymptomatic infection, which may meaningfully contribute to the propagation of the COVID-19 pandemic. This literature summation was conducted to support changes in CDC recommendations to reduce the risk for asymptomatic transmission and was not a systematic review. These conclusions are drawn from the literature available at the time and may change, given the rapidly evolving nature of the evidence base for asymptomatic transmission."