I'm a total beginner and this is my first time planting watermelon. I was excited to see that they actually came in, but they are all yellow. I'm pretty sure I didn't plant any weird hybrids or anything. Are they supposed to be yellow or did I do something wrong? I admit I didn't do anything special to them. I just planted and watered them. I honestly didn't think they'd grow, but now that they have, I thought they'd at least be green.
Watermelons can come in several colors on the inside. There are red, orange, yellow and white. It sounds like you may have just purchased a yellow variety. Nothing wrong with it, and it should be just as tasty. Enjoy!