I can vouch for the Single Seed Centre (Worldwide-Marijuana-Seeds) and Attitude, both are wonderful. SSC/Worldwide typically has lower prices on single seeds and is better for ordering just a few seeds or a mix. Attitude usually has better prices on full packs from most of the better known seed companies. Attitude also has superior shipping options.
I would not worry about getting in trouble ordering seeds, even if they are seized (which isn't likely). AFAIK most mail goes through US Customs in NY (although it is possible there are other checkpoints), so if it does get seized that is where it is most likely going to happen. The point is that for things like seeds, most pharmaceuticals and other minor sorts of 'contraband' (unless we're talking vast quantities) they will simply remove it and instead you'll get a "love letter" stating that such and such is not permitted for import and has been seized. Customs doesn't communicate with any district attorneys office, probably not even in NY and certainly not in Texas for little stuff.