The Whitefly is attracted to a wide variety of plants so there is not any one that would make a good trap crop. Because Whitefly is resistant to many pesticides control can be difficult. Perhaps the link below will be of some help.

Here is a link that might be useful: About Whiteflies

"I'm a first year grower..." It takes time to establish a natural balance of pest control. First, you have to have pests present for beneficials to show up. So battling them is actually counter-productive, in the grand scheme, although may help today/this year.

Chartreuse sweet potato might work for a trap, especially if struggling, maybe in a pot. Whiteflies LOVE that stuff, and struggling plants are usually the target of some type of pest attack. Whatever trap plants you might try, I'd put them in pots, and/or treat as poorly as possible w/o killing.

Also, try to avoid monocultures and rows. Don't put all of your tomato plants, for example, next to each other. If pests find one, they might not find the others. Even if you only have one general spot for gardening, alternate plant types if possible.

Trap plants are sorta like Japanese beetle traps. If you plant something particularly attractive to a pest species, you may invite them to that area of the garden when they normally might not have been. Even though they prefer on type of plant over the other, they are not that choosy they won't move on and infect other things.

Absolutely true. Judo asked about dealing with pests already present.