It's not simply about having a recommendation come from a professor or adviser from undergrad or a master's program. It's having recommendations
from those people who can speak to your abilities, skills, and knowledge relevant to performance in graduate school. This can come about in various ways, from the aforementioned professors, to the professor in a lab where you volunteered, to the PI of a research project you worked on in a post-bacc RA job, etc. You want them to reference your skills as a
researcher who has mastered the basic skills needed as a foundation for more
advanced skills and knowledge taught in grad school. You want references to
your academic abilities that show you can master difficult material in dynamic ways, demonstrating your critical thinking skills and intelligence. You want them to discuss you role as a subordinate/mentee who can receive
supervision and constructive criticism well and grow from it, showing your
maturity level, humility, and willingness to learn from others. To some degree you also want to be discussed as a budding psychologist, showcasing your passion for the field and a mature understanding of what grad school and careers in psychology are like.
Do you have any experience from during or after undergrad with people who could offer these kinds of recommendations?