To clarify:
I still have the lunchbox, not the obsession.
I’m about the same age as WhyNot and she is right about what sorts of lunchboxes all the other girls had. Not me, though. 5 year old BetsQ had the same Space: 1999 lunchbox as Accidental Martyr. (Good job, Mom, for letting me choose my own thing.) I had one other metal lunchbox, but don’t remember what was on it. I took a brown bag from about third grade on.
Back before I started buying my lunch, I carried a Sesame Street lunch box. 
God bless you always!!!
Holly
Either I or my brother had a plastic Muppet Show lunchbox. I can’t remember what the other one was. Happy Days, maybe?
I once had a wonderful Yellow Submarine lunchbox.
I carried lunch boxes in the 70’s. Most were TV show themed:
Little House on the Prairie
The Waltons
Grizzly Adams
Also, Holly Hobby, which wasn’t a tv show…
There were probably a couple more. I think we got a new one every year, as a back to school thing. I stopped using one after elementary school.
I had The Bionic Woman.
I’m embarrassed to say, but apparently not too embarrassed to admit that I had a Partridge Family lunchbox in the early '70s when the show was hot.
Perhaps my mom’s rationale was “A little ridicule by his peers will give him a backbone”. I did have a little crush on Laurie for a while there, so I can’t blame my mom too much.
Happy Days lunchbox.
Brave Eagle. Based on the1955-56 TV show.
Boy, I really loved that lunch box.
As mentioned, I also had a Happy Days and Holly Hobby lunch box. One I haven’t seen yet that was my favorite was my Scooby Doo! Loved it!!
E.T metal
My lunch always had homemade cookies in it. My friend Mark’s lunch always had a little bag of Fritos. We traded those items almost daily, and I’m pretty sure we both thought we were getting the best of the deal. My mom never bought chips, and his mom never baked cookies, so naturally we each thought the other’s “dessert” was better.
Walt Disney World. I remember I had to use a paper clip to keep it from opening up and spilling my lunch all over the hallway. After that one rusted out I had the red plaid box.
My brother had the Disney School Bus.
Hey, you were ahead of the curve, you had yourself an American bento box! Now, the color choice was rather…unfortunate, but the 70s had its own unique palette. Also, your mom probably didn’t spend time to elaborately arrange the lunch ingredients into cute shapes.
It’s rather odd. I know that I had at least one lunchbox with a thermos, because I remember that I was expected to rinse that thermos out promptly when I got home from school each day. But I can’t remember what sort of lunchbox I had. I seem to remember that the thermos was a rather generic one, not one with a character on it. I know that I frequently bought the school lunches, as my mother believed that a hot lunch was more nutritious than a cold one, and she also believed that the school lunches were cheaper than an equivalent meal prepared at home. I remember reading the menus printed in the paper, and deciding which lunches I’d buy, and which days I’d take my lunch, so I’d think that I’d remember the lunchbox. Nope. I really don’t. I know that I occasionally took a bagged lunch, though.
When I started high school, I always ate either the school lunch, or I ate off campus.
Paper bag only.
A plain green lunch box with matching thermos.
Mostly I used paper sacks, but one year I did have a lunchbox–a Donny and Marie just like this one.
Empty bread bag. Any fancy lunch box would have been lost on the first day I took it to school. I was a pretty forgetful child.
I first had the mailbox, then the metric system. Yes, I was a dork.