I'm not sure what you are talking about.
Are you talking about edge joining the planks to make wider boards? If so, all that is needed is the glue. If done properly, a glue joint will be better than a dowel. The dowel will create a weak point if the boards want to warp out of shape and same goes for biscuits.
Are you talking about joining one side to another at 90*? If so, you can mortise and tenon or 1/2 dado joints.
Tony B Retired woodworker, among other things.
"Strive for excellence and settle for completion" Tony B