Here are a few from my file:

Seed collages - Using seeds, beans, seed packets if available make a collage

Muffin Liner Flowers - Glue a muffin liner to a piece of paper, add petals, stem, leaves (Yellow liners make great daffodils)

Provide silk flowers, pots, shovels, hats, seed packets, watering cans, etc to liven the drama corner

Explore worms and dirt

Add lavender essential oil to a batch of purple playdough for a great smelling experience

Handprint tulips - Paint entire hand, fingers pressed together for flower, and outside edge of the hand green for the stem and leaves.

Any recipe that uses fresh produce that can be grown in a garden