Question
I took over taking care of a raised bed at the school I work in.  I don't have any idea what I'm taking care of.  
The plants are about 3 ft high big soft heart shaped leaves, the leaves are about every 4 to 5 inches growing on the main stem, the leaves are about 4 to 5 inches big,they have little yellow flowers, that look a lot like cucumber flowers, then when the flower drops, they grow into what look like a sunflower bud

Answer
Sounds a lot like Velvetleaf, Abutilon theophrasti, particularly if the leaves are soft or hairy. If this is it, the flowers will have 5 petals, and inside the sunflower-bud-like structure would be lots of smallish, heart or kidney shaped seeds and the structure itself would be blackish.

Velvetleaf is a weed, and a serious one where corn is grown as a major crop. If this is indeed your plant and you live in the corn belt you really need to at least remove the seed heads (those sunflower-bud structures) or probably better pull the whole plant. However, it is easy to grow and hardy, the soft leaves would appeal to children, the flowers are cheerful, the seed heads unusual, and as far as I know it is not in the least poisonous, so it could work in a school "wildflower" garden.

If you can send me a picture of this plant and/or whatever else is growing in your garden and the state or region you live in I may be able to help you figure out what to keep and what to pull. If you are in the eastern half of the US, north of the Gulf Coast states I can most likely identify anything you may have that is poisonous.