Here's a "quick and dirty" PVC Instructable describing how to make a handy PVC lawn and leaf bag holder. My design is not quite perfected, but it has given me 15-yrs of reliable yard service.

Decades ago, the Hefty bag folks offered a tubular metal lawn and leaf bag holder, for a small fee. I loved these holders, but the metal frame tended to bend and rust. When Hefty stopped offering these, I kept the rusted remains of my last one to make a PVC clone. The picture above shows what I ended up with.

Supplies

1/2-in Sch. 40 PVC Pipe (my project- Silverline PVC-1120 PR.600 PSI)

4 x 36-inch straight sections (legs)

1 x 18-inch straight cross section

1 x 17-inch straight cross section

4 x end caps for leg

4 x elbows (to attach cross sections to the legs)

2 x Cotter Pins approx. min. 2-inch (Stainless Steel preferred)

2 x 8-inch Chains (Stainless Steel preferred)

4 x small sheet metal screws (to attach chains to legs)

Step 1: Assembly Steps

Assembly diagram is provided above.

Prior to assembly, each of the four legs needs a hole drilled all the way through at 15.5-inch down from the top for the Cotter pins to go thru.
Assemble to the two sides as shown
Use Cotter pins to attach two sides, whereas as the 17-inch cross beam leg goes inside of the 18-inch cross beam leg. The Cotter pin eye is placed on the outside (to prevent puncturing the lawn and leaf bags). The Cotter pins are bent flush to the inside legs, and covered with white Duck/Gorilla tape or equivalent (see photos).
Drill a small guide hole for the screws to hold on the leg-limiting chains (possibly it is better to do this before assembly of the sides.) The guide hole is 12-inch from thE leg bottom. The chain is 8-inches in length.

Consider gluing the PVC parts together, but this is optional if the fit is tight enough.

Step 2: Final Comments/Design Improvements

Photo shows folded holder in storage.

I like to use larger 45-gal contractor bags (eg; from Walmart), but regular lawn and leaf bags are fine.
The 18-inch and 17-inch cross beams should possibly be another 1/2-inch different (so say consider 18.25-inch and 16.75-inch cross beam sizes)