Cesar Chavez day is March 31st. He's an important figure not just in American labor history but also the civil rights movement. A recent movie about him could also be used as part of a lesson.
Here are some nice ppts reviewing his life. Students can read the Gif Lingua book (teachers register to download worksheets / ppts of all 2,000+ books).
There is a nice timeline worksheet - students can research his life and complete the timeline.