Lettuce killers

Lettuce killers

Hi Everyone! This is my first post, and I come with questions. My garden has been pretty easy for the last couple years - everything seems to grow well and nothing gets eaten. This year, however, my lettuce is getting attacked. Every day I notice 1 or 2 plants that are wilted, and when I get close I see that their stems have been severed at the soil line. My first thought was cutworms, but so far I haven't been able to find any, even poking around at night with the flash light. I have, however, found a couple grubs and what look like baby grubs (I don't know what they actually are, but they look just like grubs only much smaller). Would grubs do that kind of damage? Or do I just have really stealthy cutworms? Or might it be something else entirely? I've tried a an organic spray (garlic, clove oil & some other stuff), but they haven't really been effective. I'm afraid to try any of the non-organic stuff. I know it says it's safe for vegetable gardens, but it freaks me out to put stuff on my food that comes with a warning about not touching it with bare hands or letting animals or children near it. :/ Is this stuff really safe? Also - whatever it is only eats the lettuce in the beds that I mulched with mostly dried grass clippings, and the problem didn't start until after mulching. Did I possibly introduce some eggs into the garden when I did so? Or did I just create a better hiding place for the bugs? (I'm in zone 5B, by the way)
Zenni Optical review with pictures!

Zenni Optical review with pictures!

New and plant identification?

New and plant identification?

Plant ID

Plant ID

Current state of (container) garden.

Current state of (container) garden.

Repotting Question…

Repotting Question…

What is this flower called?

What is this flower called?