Agave attenuata

Agave seeds are gone.

Although it's a youngster it could grow up to be an Agave horrida. It's got those odd "teeth" and the right color and leaf shape. If this is a young A. horrida then it will some day need to be planted outside as they get rather large as in six feet in diameter and three to four feet in height.

Agave americana (century plant) is a possibility., But so is A. scabra and several other species. Agaves are often very difficult to identify when young. Care: water when dry. Use very quick draining soil. Give it as much sun as possible. Practice benign neglect: leave it alone and it will thrive.