" I bought plants (bean, pepper, corn, okra, eggplants, etc) and planted
them in late early May. No new growth since planting. Instead, they have
yellow leaves, thin stems, or just plain dying."

These are what's commonly known as "hot season" crops. They need warm soil temps (55-60F minimum) and also warm air temps, especially overnight. If planted out too early, they will not grow, will often display reddish-purple tints to the foliage and can even die off.

Even in my very mild climate (last frost is end of March), these types of crops are not recommended to be planted out until at least Mother's Day but preferably waiting until the beginning of June.

So you two are basically saying I won't have to write an Ode To A Dying Garden? Awesome! I'll give it another go with new plants which I'll plant next week (weathering permitting). Thank you!

My plants are not doing too well either. I'm looking at pictures of last year garden and those were way ahead of the garden sitting out there sulking right now. Our April and May have been horrible. last night it dipped down to 38 degrees. I had to cover my tomatoes. Tomato is the only warm weather crop that i set out. I bought eggplants, tomatoes, peppers from the green house on 4/30. that's when i normally buy them. But this year i couldn't set them out since it's been too cold. I had to set the tomatoes out since they were getting too big in the pots. Peppers and eggplants are in and out of the house as the weather allows. Everything else seem to be growing slowly too. I'm hoping the warm weather (if it ever makes it here) will get things going. So don't loose hope. Things will start to grow once the conditions improve.

No need to write an ode yet. Those plants are wanting warmer air and soil temperatures. My fall-planted garlic and leeks are going gangbusters, peas, chard, and lettuces and many of the herbs are doing well, too. But the warm-season veggies are still in the greenhouse; there's nothing to be gained by planting them out before the soil warms up, as they'll just sit there and sulk until it does.

So my next questions are: should I leave the plants in? For example, some of the pepper plants still have some green leaves on them - should I expect them to bounce back up once the soil warms up, or is that wishful thinking ?

Let's see what others have to say, but my feeling is that they've already survived the cooler temps, and there's probably (hopefully) nothing worse coming along, so spare them the trauma of further transplanting and give them time to perk up and get growing. If there are any really chilly nights ahead, you could try protecting them with cloches or either a frost cloth or sheet, but that probably isn't necessary at this point ... unless you're way up in northern Jersey, in the mountains, where it might be colder.

I started some tomatoes inside, bought a pepper and eggplant, and started lettuces outside. The lettuces are doing fine, but slower than ever. The eggplant is outside, but sheltered. The pepper and tomatoes aren't going outside until Memorial Day at the soonest, but in other years they would be planted in the ground after Mother's Day. Patience.