We read "Lemons Are Not Red" by Laura Vaccaro Seeger, "The Red Lemon" by Bob Staake, and "Maisy Makes Lemonade" by Lucy Cousins. All fun books that my boys loved! We talked about lemons and limes and all the things you can do with.
For a craft we made stamps out of lemons and limes. You cut lemons and limes in half, dip them in acrylic paint and stamp away. I had my boys decorate a large letter "L" with their stamps.
Then we made real lemonade! They thought it was delicious and were proud they'd made it themselves!