L.H.
Good Morning A....a lot of schools these days have a policy that if invitations are sent to school to be delivered then the whole class has to be invited. Sometimes kids get their feelings hurt when they learn that certain kids got invited and they didn't. Additionally, if the party is somewhere like the "Bouncy Place" then the parents are charged pretty much the same amount regardless of how many kids come so they figure just invite everyone. My kids love the bouncy place so anytime they can go for free is a bonus for me.
So there's a couple ways to look at it...first, I'm sure the parent and birthday child will not mind at all if you don't go. The mom was most likely just trying to be polite by inviting everyone.
Second...if you do go, just buy an inexpensive gift (you can get little pet shop stuff for like $5--I'm sure there's boy stuff for $5 too). It's a great way to meet the other parents that your child will be growing up with. My daughter is now in 3rd grade and gets invited to parties like this all the time. I like that I know so many of the parents and feel like we all look out for each other's kids at school events or wherever.
So to sum up...don't stress about it. Just do what you're comfortable with and I'm sure nobody is going care or judge you for what you decide. When it's your daughter's birthday though and you don't want to invite everyone (I'm always uncomfortable with that too) either hand the invitations out to the kids you are inviting outside of school and try to talk to your daughter about not talking about it alot in front of the other kids so no one gets their feelings hurt. Or, invite everyone and put something like "no gifts necessary--just come and have fun" on the invitation. Everyone always shows up with a gift anyway but it doesn't seem like you're expecting gifts.
I hope this helps! Have a great day!
L.
P.S. Stay at home mom to 8 and 5 year old girls. Married for 10 years.