Wow that makes me intensely jealous! Congrats on the find. I've been collecting arrowheads my whole life and I've never found that many in one day. My family has a place outside of Mertzon that has a dry creek bed running thru it, and every now and then I'll find a few really nice ones down there. The neighbors land has a burial mound on it. . .I feel like it's only a matter of time before I find something amazing. . .
Seriously tho, congrats. That's a lot of history laying on the ground right there.