What Wildflowers can be planted in the spring from seeds?
There are many wildflower seed mixes that are readily available that can be planted in the spring. If a list of the seeds is available then it might be wise to investigate if these will germinate in the spring. Many may not come up or will not germinate until fall.
Planting native wildflower seeds can be difficult because the seeds may need a special treatment in order to germinate. This might mean they need to be chilled, need to be scarification or may need stratification.
This is why most wildflowers are planted in the fall, usually September or October, depending what zone they are being planted in.
Here are some threads that might help with understanding why: