Alvin Kamara is doing his part to brighten up an NFL official's week after the Saints star accidentally broke the guy's leg during a game on Sunday ... sending a signed ball and jersey his way -- with a well wishes note too.
The man -- Nick Piazza -- received the gifts on Wednesday, according to NOLA.com's Jeff Duncan ... just three days after Kamara barreled into him in New Orleans' tilt against the Lions, seriously hurting him in the process.