Never had experience with them. Sorry to hear that. Seeds are best found or bought from companies that specialize in tree seeds. Usually you can even call and find out where the seeds originate. Sometimes it’s supplied in the info section as well.
If you’re looking to buy a native specie or common landscape specie. Getting them directly from the tree is ideal and it can be fun and rewarding. Also no guessing the genetics should be good for your area. My various elm species, trident, and bald cypress are all from local collecting.
Malls and parks are good public resources for collecting if you ever are interested. Nobody will care. I asked the owner of a car lot if I could collect seeds from the trees on his property and he was happy I’d pick them up lol. He had no idea what I was asking at first