I think for your needs the best site is the USDA site.
Click on the link below.
Then in the search bar on the left side type in Moss
Then click on drop down to insert Common name
Then click GO
You will find a list of all the mosses they have in their data bank. Not all have images but they have more images of living mosses than any other site I know of and their info covers US and Canada

Here is a link that might be useful: USDA search page

The University of Wisconsin Freckmann Herbarium has a pretty good site with pics of the more common ones.

Here is a link that might be useful: Wisconsin Bryophytes