Short answer: There is no Jain rule that bans jeera (cumin seeds) or neem. The main dietary principles for lay Jains focus on non-violence (ahimsa), avoiding root vegetables, eating fresh and during daylight, and avoiding intoxicants. Jeera as a spice and neem leaves or products are not listed as forbidden in standard Jain guidance. Of course, individual practices can vary by sect (Digambar vs. Shwetambar) or family maryada, so when in doubt, check with your guru or local community. You can read more here