Rihanna's making sure her kids learn about their roots ... taking them back to her native Barbados for a visit filled with sweet treats.

The singer-songwriter was spotted relaxing on the island ... wearing a gray top over her swimsuit and walking right up to a coconut stand where she ordered treats for one of her sons and her daughter, Rocki.

The crew sipped out of coconuts ... and Rihanna was beaming at her son when he dug into the sides of his snack.

Of course, it's hard for Rihanna to go incognito anywhere ... let alone in her home country -- but she happily stopped for some pics with the locals, flashing her celebrity smile as she posed.

Rihanna also enjoyed traveling around the island the old fashioned way ... eschewing a private car for a ride on a bright yellow public minibus.

Bottom line ... the whole family found love -- and coconuts -- on their island vacation!