NFL's Will Smith -- Fans Create Makeshift Memorial ... At Scene of Shooting

A makeshift memorial to ex-Saints player Will Smith has sprung up at the New Orleans street corner where he was shot and killed this weekend ... and it continues to grow.

We spoke with John Harkins -- owner of Harkins the Florist Inc (a flower shop near the memorial) -- who tells us fans and non-fans have been streaming into the shop all day Monday buying arrangements to contribute to the memorial.

But it's not just flowers ... people are also leaving Saints memorabilia, gold and black balloons and signs condemning the senseless violence.

Smith was killed Saturday night during an altercation following a car accident. Cops have arrested the shooter, who insists he only fired in self-defense.