In the Group Forums, as well as here in the main forums, there is alink in the bottom right when you post that says "Additional info on using these tools"
It leads to here:
where it shows that we can insert tables into forum posts.
I do not see the option to do that in my group forums, is this no longer available?
We don't have that option in the forums (neither group nor public), but you can make a table in your blog. If you'd really like to you could copy and paste the table from your blog to your forum post (which is what I did below). Sorry for any inconvenience!