Yes, pits and seeds (peach, avocado, olive, etc.) are fine. Not all composting is the same. Our compost naturally gets to very high temperatures for long periods of time making seeds in the pile not viable. Everything gets broken down. Backyard piles normally can't achieve this which is likely why you thought you couldn't put them in. Again, not all composting methods, maintenance and mixes are the same, so thanks for asking first!