Gingersnap has a root beer fragrance and was introduced in 1965.. Maybe a little too late, but I've found memories aren't always accurate. There's often a little blue streak under the beard. It's quite a bit darker when first opening, and pales out a bit with age, so you'll see a lot of variation in pictures.
"Brown" iris were very popular in the 40's and 50's, I believe.. There are many..
I recently ran across this one, but there is no mention of scent, but the coloring matches your description..
https://historiciris.org/galle...
Seems to me there was a subject line some years back regarding scented Iris, or maybe root beer scented iris.. My download speed is frustratingly slow tonight, otherwise I'd try to seek it out for you.