geranium can be snipped off at the joint and start to root in just a glass of water. set on a window sill. easy no brainer plant. or Parks seed has geranium seeds.
Park Seed: Seeds and plants for vegetable, flower, annual and perennial gardening.
and here is a real fun plant to grow near or around a pot plant
cleome. or a spider flower. check out the leafs on this plant. thay can confuse people.

the leafs kind of look like a pot plant.
and grow tall enough to kind of hide some in there. GREAT for out door growing. starts from seeds a self seeding annual.
hope this helps.