I think the white thing you're seeing is a pumpkin seed. Hamsters tend to love the pumpkin and sunflower seeds in their mixes so it's no surprise she chose one! A fun seed mix to feed is millet, hamsters love chewing the spray millet sticks. You can also give "foraging mixes" made for hamsters at the store, as long as they're safe
insects like mealworms and crickets also make excellent protein supplements if that's what you're looking for. There's lots of safe food lists you can check for online, and it can give you good ideas on what to feed!