In medium saucepan, stir together strawberries, rhubarb, lemon juice, and maple syrup over medium heat. Let mixture come to a simmer, stirring occasionally.
Once at a good simmer, let jam cook for 15 to 25 minutes, stirring frequently.
About halfway through cooking, break up fruit with fork or potato masher.
Once jam has finished cooking, turn off heat and gradually whisk in collagen.
Transfer to heatproof container and let cool to room temperature.
Once cooled, cover and refrigerate for up to 1 week.