plumbing - how to tell where a blockage is???

"when we pop the cap to the cleanout in the front yard."

This indicates that the stoppage is further downline from this point.

"i tried snaking both ways"

If you are referring to the fitting in the flower bed, this fitting should not be a "T" but a "Y" and allow snaking downstream, which is the direction of the obstruction. Depending upon the distance to the street from this fitting, you may need a 100' snake with a 3" cutter.

If the water comes out of outside cleanout, the clog is farther down the pipe than that, between the cleanout and sewer tap, probably. Put a good cutting blade on your snake to cut through the roots that have probably grown into the pipe, at the cleanout and towards the street.

DUDE!!!! sounds like your drain field is clogged. if you can open the cap in your yard and CRAP comes out all over the place. sounds like its flowing just fine. Do you have trees with in like 20 feet if the drain field, or have you ever had the septic sucked out? I know that if you don't do this the drain field can get clogged up with solids an it won't let the water flow out very quickly. That's what happened at my mom and dads house!

the clog is after the cleanout, to the sewer. you need a large rodder, maybe 5/8ths or larger.

call a pro.

You sure when you snaked out you ran it both ways? You may have to get a plumber who dose visual inspection with a cable camera . Like a colostomy.