Cold resistant plants?

Cold resistant plants?

I was sorting my seed packs out and noticed that peas, lettuce and other things say "plant in early spring." Does that mean they'll be ok if we get a couple of frosts or do I need to wait and plant them with things that say "after last frost?" I've never grown most of this stuff before so I'm a little lost. I'm eager to get things into the ground straight away but I will cry if everything dies if we get a cold snap. We live in Zone 7.
Harvest!

Harvest!

violas

violas

plant id

plant id

please and thank you

please and thank you

Today’s harvest.

Today’s harvest.

Suckers

Suckers