Peas can grow on the ground, which might be good if you're a kid, but I find I like to bend over less than I used to. Picking peas and beans from a trellis keeps them cleaner and saves time and strain in the picking.
I harvested some 2" bamboo from the overgrown alley at my old house in the Burch Ave. neighborhood and cut it to about 8' long to get it home in the truck. The peas were already planted and had grown about 12" high and were waving around searching for something to climb.
As you can see in the picture, I set a pair of bamboo at each end of the 4'x4' raised bed and used tie-wire (twine would work fine too--I just used what was handy) to make an "A" frame. Just cut a piece of wire long enough (about 16" or so, length of wire will depend on size of bamboo) and wrap around once and twist the ends together.
An advantage of tie-wire is that you can then use a wrench to grab the twisted ends and twist them tighter to snug up the pieces of bamboo. I then used a third bamboo to hold an "A" up temporarily by leaning them together ( a helper can be useful to hold things in place while you tie them, but if you're handy and take your time to think out your steps, you can do this alone if need be).
Another piece of bamboo that reached from the bottom of one "A" to the crossing point of the other "A" was tie-wired (and tightened with pliers). A diagonal like this is necessary to keep the whole thing from falling over. The final piece of bamboo (cut with a saw to the right length) straddled the top of each "A" horizontally and was tied and tightened.
With the bamboo frame in place, I just needed something to drape on it for the peas to climb on. I had a short section of galvanized fence left over from a project that fit in both dimensions. Any kind of netting would work or you could use jute twine to weave your own netting. I've seen one gardener use twine to weave a netting that looked like a big spider's web--so there is no law that the netting has be be composed of a series of rectangles or parallel lines. The peas won't notice.
In fact you could use a tangle of branches laid against the bamboo if you've been doing some pruning. Peas and other vines evolved clambering up twigs and branches anyway, so they'll be right at home.
And then if you've planted Sugar Snap peas you and your sweetheart can stuff your faces with the green candy in May/June while sitting on the porch admiring your handiwork.