Ok, I'll chime in here. A couple updates to Chris's post. Murphy's is $30 but no fee for spectators. Del Valley's scoring tower just blew over and destroyed it. So their current schedule is unknown.

I live in Buda, and it takes me 35 minutes to get to Del Valley and 40 minutes to get to Murphy's. These two mx tracks are roughly 15 minutes apart.

I've ridden at Cloudcroft many times and you won't find anything like that around here.

Another place to check out for just trails is Powell's Offroad Park. It's fairly new and in the same area (Cedar Creek) as Murphy's they have a Facebook Page

Definitely check out the AMSA family days. Just park anywhere and introduce yourself to anyone around you. Very friendly crowd. If you're into mountain biking there's groups that do that too.

If you are into competition, there's TORCS (hare scramble) and the enduro series. Both have forums on here. TORCS next race is May 21/22 in San Antonio at Zars ranch. Which is a cool place to ride.