The best snowboard camps are in Mt Hood, Oregon and Whistler, British Columbia.  Both of which you would want to fly to from Kansas.  There are also camps in Girdwood, Alaska, New Zealand.  You may get lucky and find something going on at Arapahoe Basin, Colorado which may be driving distance from you.  They (and Whistler) would be the best for North American Freeriding in June.  I couldn't find anything on Camps at A-Basin, but you could contact them to see if they have anything going on in June.  They like to stay open through July if possible.  The camp at Mount Hood is really popular but focuses more on freestyle.

Now, if you want good freeriding and have the cash, head south to Chille to a place like Portillo.

Here are some more Summer Snowboarding Camp resources:

  -  <a href="http://www.dpbolvw.net/a073r09608OQVTTRWWOQPTVYQWQ?url=http%3A%2F%2Fwww.backcountry.com%2Fstore%2Fnewsletter%2Fa279%2FSnowboard-Summer-Camps.html" target="_blank">Snowboard Summer Camps - Article from backcountry.com[/url]
<img src="http://www.awltovhc.com/ld104drvjpn8AFDDBGG8A9DFIAGA" width="1" height="1" border="0"/>

  -  http://www.mysummercamps.com/camps/Sports_Camps/Snowboarding/index.html