I agree with another commenter, celery was also a hit with our budgie growing up! They absolutely loved chipping away at it

I haven’t had a budgie for many years but the last one we had absolutely loved chickweed from the garden.

Sunflowers heads! Best of all you let them dry first so you can have all the benefit of sunflowers, allow them to dry and then hang the dried sunflower head in the cage. They are high in fat so more of an occasional thing but make for a very happy budgee.

our budgie loves celery. He has a mixture of fruit and vef etc but he doesnt eat it much where as celery leaves he will demolish.