Is this in Knoxville?

Yup, it's in Knoxville.

Great! I'm up for a plant sale- can anyone come up with an address? I'm totally not familiar with Knoxville!

Racheff Gardens are located on Tennessee Avenue, off Western Avenue between I-640 and downtown. It's down in the old heavy industry area just north of downtown Knoxville, the last place you'd expect to find a public garden.
More info on the gardens at the website below.
Interesting history. The gardens were created by the founder of a steel mill who lived on the mill property and had them created at his house for his family and the workers. They are beautiful and worth the trip.

Here is a link that might be useful: Racheff Gardens

Neat! Is it a big sale, like one you should bring your own cart for?

It's a very small sale, but usually packed with very interesting plants -- especially natives. They have wagons available. Be sure to get there early!

I can't remember nearly all of the stuff I've bought there over the years, but a few that come to mind right now are Rosa palustris, dwarf blueberry, Corylopsis spicata and Corylopsis pauciflora, Western sand cherry, herbs, and many others.