Need advice on what plants to use for our school gardening club

I am a teacher and I started a gardening club at our school this year. We meet in a few weeks for the first time. We have a large raised bed area that the school let us take over, but they requested it look nice and landscaped, and thar we put in the right flowers so there is always something blooming in spring, summer, and fall.

A couple constraints though:

1. we don't want anything invasive, native plants preferred but not a deal breaker if it's not
2. we don't have any budget so I have to buy everything with my own money because we haven't been able to get any businesses to donate anything despite our best efforts and we don't have time to fundraise

HELP!