There is a place in N. New Jersey called Well-Sweep where I got mine. Unfortunately, it was a tiny baby and in spite of my trying my best, she didn't survive.

However, they do mail order. The people I've met there are wonderful and I can't say enough good about the place. They have a website:

Here is a link that might be useful: Well-Sweep Herb Farm

I need to know where I can buy pennyroyal in my area of Tampa FL.