https://en.wikipedia.org/wiki/Enaree
So, I always wondered what I would do if the Apocalypse broke out and all estradiol medication was gone.
I thought that maybe drinking the urine of pregnant mares would do the trick, but you’d die of overhydration long before you could get proper levels. However, it turns out that, similar to the production of Premarin, you could use the urine to make estrogen cheese. 
Unfortunately, I don’t really like cheese. So I’d be screwed either way 
There's also plants with estrogenic effects. Anise oil comes to mind, it is considered safe for flavoring, and people did manage to hugely increase its potency.
Sounds more appetizing than the urine cheese but I’m not sure if the effect is strong enough, and the stuff in the link is definitely way beyond what a bunch of queer horse riders in antiquity could do.