The short answer
Yes — sweetcorn is a beloved treat, but it's starchy, so keep it in moderation.
Why
Budgies go crazy for sweetcorn. It's perfectly safe, but high in starch and sugar, so it's a treat rather than a staple. Fresh or thawed-from-frozen is best; avoid salty canned corn.
How to feed it
Offer a few kernels or a small piece of cob (many budgies enjoy pecking straight off the cob).
How much & how often
A couple of times a week.