Preheat the oven to 375°F.
Lightly coat a baking sheet with cooking spray.
Unroll the crescent roll dough onto a lightly floured surface.
Press the seams together gently to form solid rectangles of dough.
Cut the dough into 4 columns and 6 rows, creating 24 small squares.
In a medium mixing bowl, combine the mayonnaise, chopped green onions, softened cream cheese, cayenne pepper, and fully cooked crabmeat.
Mix until the filling is evenly combined.
Season the crab mixture with salt and pepper to taste.
Place one small spoonful of the crab filling in the top corner of each dough square.
Starting at the corner with the filling, fold the dough over the crab mixture.
Tuck the corner under the filling as the dough is rolled.
Continue rolling until almost reaching the opposite corner.
Bring the opposite corner back over the roll to enclose the filling.
Press lightly to seal the dough.
Arrange the filled crescent pieces on the prepared baking sheet, leaving space between each piece.
If desired, brush the tops lightly with egg white for a more golden finish.
Bake for 10 to 15 minutes, or until the crescent dough is golden brown and fully cooked.
Remove from the oven and allow the snacks to cool for a few minutes before serving.
Serve warm.