This and the matter above are

This and the matter above are a bit out of our range, but your situation suggests (more specifically than the one above) that you may have a break in your waste pipe to the street/main line. The grass seems to indicate that you are getting reflux, so to speak, from the lawn that covers your waste pipe. The eventual drain you mention is natural: some of the waste water is slowly seeping out of the pipe at its break and into the ground. Snaking might get your some time (delay a possible replacement), but here as above, we can not be absolutely certain. Best to call a professional.