The easiest vegetables for you to grow will depend on your climate and garden space, but I recommend lettuce and most other greens, radishes, pole beans, summer squash, tomatoes and cucumbers for new gardeners.
The best seeds to use are the ones you have, and seeds have become more challenging to find, so use whatever source you can. If possible, I recommend buying seeds from small local seed companies in your area. The varieties they sell are well suited to your climate. When deciding what seeds to buy, choose things you love to eat, and start with a relatively small number of mostly easy-to-grow plants. The easiest vegetables for you to grow will depend on your climate and garden space, but I recommend lettuce and most other greens, radishes, pole beans, summer squash, tomatoes and cucumbers for new gardeners.