Additional rainfall observations are available that are not found on the Weather Underground site.

Community Collaborative Rain, Hail, and Snow Network

A non-profit, community-based network of volunteers of all ages and backgrounds working together to measure and map precipitation (rain, hail and snow).   By using low-cost measurement tools, stressing training and education, and utilizing an interactive Web-site, their aim is to provide the highest quality data for natural resource, education and research applications. CoCoRaHS is now in all fifty states. 
National Weather Service provides daily hydrometeorological summaries:
National Weather Service Daily Hydrometeorological Products
NOAA National Weather Service also routinely puts together event summaries after a big rainfall.
National Weather Service Public Information Statement