I did not have a list like what my friend was talking about from the top off my head, but I felt fairly confident that I could come up with a good quick list. I started rattling off some titles, and my friend pointed out that every one I named had animal characters. She wanted human families. I quickly realized I was going to have to do a lot more work to come up with a list for her. What I found from noodling around was a lot of great books that are about different families, or about having two mommies, a dad away in the military, divorced parents, or adoption. And these books are fantastic.
As children get older, many schools and libraries have bigger collections that show more LGBTQ characters, stories, and families. The YA publishers have a lot of titles out right now that address the issues these teens face, but also just show these teens as a normal part of the American landscape. While this list does nothing to help my friend with her three year old son, it is a great list that is growing all the time.