The leaves look like agave, but I don't think A. attenuata, which is the foxtail agave. It makes a huge, thick, bushy looking flower stem, for which it is called foxtail:
https://1005klahanie.files.wordpress.com ... -bloom.jpg
I couldn't find a picture that really matched yours -- many of the agave pictures show giant flower spikes, like 6 feet tall or more. But there are a lot of different agaves - utah agave, arizona agave, A. americana, A. mexicana, desert agave, A. salmiana, A. ovatifollia, etc etc.