Red Clover

Trifolium pratense
Like many plants classified as "weeds", red clover is packed with vitamins and minerals. Red clover flowers may be made into a calming and tonic tea and the leaves have all the benefits any leafy green vegetable has.
The most direct effect red clover might have on one's libido is the phyto-estrogens it contains, which the body may use to build its own hormones. However, phytohormones have not been definitely shown to have any significant effect on hormone levels and shouldn't be considered aphrodisiacs.