Many gardeners were up in arms over aggressive types. Others praised oxalis. Since some types are extremely aggressive, it's a good idea to plant yours in a pot. They prefer more shade than sun in the summer. Good drainage and fertile soil keep them happy.
Oxalis grow from bulbs, rhizomes or tubers, depending on the variety.
They are planted only an inch or two deep. The plant you sent, with leaves that fold at night and small lavender flowers, is an oxalis. It was pretty mushy in the plastic bag. Mail garden questions to Kathy Huber, Garden Editor, Houston Chronicle, P.O. Box 4260, Houston, Texas 77210.