Are shamrock orb weavers poisonous

No, you can eat them with no ill effects. They are quite good roasted.

If you mean, "Are they venomous?" the answer is "Yes." As Spiders go, their venom is not as dangerous to people as some other spiders' and a bite will be painful but not usually life-threatening. It is about as bad as a wasp sting. That is not to discount the possibility that you might be deathly allergic to the venom.

If one bites you, ice the wound and seek a medical opinion. Capturing the spider to show the doctor (for positive identification) is not a bad idea if you can do it without getting bitten again.