To my son Tommy,
Lego is the plural of Lego. If you want to add an "s" to the end you have to say Lego blocks versus the singular Lego block. You sir, definitely have the plural version of Lego. Easily one hundred pounds of Lego blocks fill these containers, and today you are in a building mood and wanted every box you could find!
Sincerely with love from your dad,