What is this plant/seedling growing from hard, oval, mottled-brown seeds?

Question

I found some seeds when running outside:

I planted one for curiosity and it has 4 leaves now:

Any idea what it is?

Answer 1

That's a castor bean, Ricinus communis. Seeds. If you have winter, they'll grow 10-14' (3-3.5 meters) in a year, with nice ball shaped flowers/seed pods. In regions without winter, they can grow to become sizeable shrubs, with roots that can damage foundations. The entire plant, but particularly the seeds, are poisonous, containing ricin, the toxin used in the famous 1978 umbrella assassination of Georgi Markov in London.

They're often used as a background plant in temperate zone gardens.