Its native range is most all of the US and Canada. It is a weed of disturbed places here. Surely there gardeners in the area who may let you take it from their gardens for free? :)

FataMorgana

Here is a link that might be useful: usda link

I live near some woods and I've never seen any and I've been to a few nurseries but no luck.

Most treat it as a weed to be gotten rid of. I wouldn't expect to see it in a nursery except perhaps those specializing in medicinal herbs. You could try asking one of the geographic based forums. There are ones for the south and possibly Alabama.

FataMorgana

And if you do find some keep it in a pot. This is not a plant you want loose in your garden. It is one of the most resistant weeds/plants there is.