Interestingly, there are similar Polish surnames, Jadrysiak and Jadryszak, but I'm unable to learn their meaning. I don't think the Russian name is a patronym, the -nik suffix suggests otherwise. The construction is similar to, for example, khleb,"bread", khlebnik, "baker"; giving us surname Khlebnikov. So for my money Yadryshnikov descends from someone connected to a yadrysh, whatever that is. A Russian dictionary I consulted has the following: yadro "kernel, nucleus", yadrysh (ÿäðûø), "nucleolus". Not likely to be the source of Yadryshnikov, but an indication that the word exists, and may have had some other meaning in the remote past or in some obscure dialect.