It's hard to tell for sure, but the middle picture looks like you have some black medic.

Some of the leaves look like they have the white ring in the leaf, so you may have both dutch white clover and black medic. I don't think anything other than hand pulling is very effective on black medic. I've tried using a weed hound, but it's tough to find the center of the plant because it spreads all over the place.

Here is a link that tells how to differentiate clover from black medic and yellow woodsorrel (another clover lookalike).

Thank you!
That link did the trick. Excellent information page.
Based on this, I determined that I had a bit of sorrel mixing in with my clover and that most of this light green clover is just young. It should turn darker as each plant matures.