I literally just watched a video about this yesterday. The youtuber said beans, butternut squash, and potatoes. Reading the comments, other people argued for replacing potatoes with sweet potatoes because those are healthier plus you can eat the greens. Other commenters replied that the natives of North America subsisted on what they called the three sisters - winter squash, maize, and climbing beans. Those three crops apparently do not compete for the same nutrients from the soil. Others made the case for adding tomatoes.