Yes, I'm sure. It says so right on the site. The tgv-europe site is a multi-language site operated by SNCF, French National Rail. One of the options is to have your tickets mailed to you. However, SNCF doesn't mail tickets to North America so you'll be diverted to Rail Europe if you choose the USA as your country of residence. And if you choose France as the country in which you will retrieve your tickets, you'll get a booking page in French.
As I said, you can book up to three months in advance. For example, if you want to travel on 15 July, you can book as early as 15 April. However, since France is six hours ahead of your time zone, booking after 6:00 p.m. on 14 April would allow you to get tickets for 15 July.
Rick Steves recommends Auto Europe--and so do I. AE is a consolidator that finds you the best rate from among the companies with which it has contracts. If you find a better rate on your own, AE promises to either match or beat it. You can book online, but it's a good idea to call their US toll-free number and ask about any specials that don't appear on their Web site.