I picked it up in person at Milborn Seeds in Brookings, SD. I like this place because you can buy individual seeds in any quantity. It also works for me because it's right along my travel route. http://www.millbornseeds.com/
The people are really friendly too. Again, being very small potatoes in their business, they still give me as much attention as I want. They also staff people trained in turf, forage, cover crop, conservation etc. I looked over my receipt, and it doesn't say exactly what kind of radish I got. I asked for "tillage" radish. I'm hoping it's the big white ones that stick up out of the ground. The rye looks like bin-run that's been cleaned.
I just started using them this year and I have been very pleased. It helps when the guy you're talking to about food plotting is also a food plotter himself.