Vickie,
I searched some of the groups listed and none had front page photos.
Perhaps it was just those I clicked on had no photos
There may be some confusion over terminology.
All Groups.io groups come with a default black-and-white cover photo of some elephants on the open plain. You see that on Beta, for example. So I'm confused over what you mean by groups that had no photos.
Here in GMF I replaced it with a photo I took of some elephants. You can upload your own in the "Cover Photo" tab of the settings page.
Like the "cover image" on Yahoo groups, it is at the top and banner-shaped. Unlike Yahoo groups it doesn't head every page of your group, only the home page. Also unlike Yahoo Groups, it doesn't get all weird if your photo isn't banner-shaped.
I would love to see the front page of any group with it's group front
page photo.. I would like to see what it looks like
Here's one with both a cover photo, and one embedded in the group Description text.
/g/shalstest-- Shal