Use any beans, or seeds,
Use a glass jar with some wet paper towelling in a tube so that it rests against the sides of the jar. put the seeds between the paper and the glass. Put something else around it to keep out the light. Keep the towel moist.
The students can examine it every day, watching the roots and stem form, with the little baby leaves coming up and turning green when they hit the light. They can also record what happens with very simple language. A really good exercise which allows students to talk about past and present, sizes, shapes, change, color etc etc.