Now blooming in several areas of the park, mostly in the northeast quarter: Crimson Clover (trifolium incarnatum), sometimes called Italian Clover. Wikipedia has this to say about the plant:
Crimson clover is widely grown as a protein-rich forage crop for cattle and other livestock. It can typically be found in forest margins, fields and roadsides.
It is sown as quickly as possible after the removal of a grain crop at the rate of 20-22 kg/ha. It is found to succeed better when only the surface of the soil is stirred by the scarifier and harrow than when a plowing is given. It grows rapidly in spring, and yields an abundant crop of green food, particularly palatable to livestock. It is also suitable for making into hay. Only one cutting, however, can be obtained, as it does not shoot again after being mown.
In Great Britain it is most valuable in the south, though less successful in northern regions.
It has been introduced into the United States, originally as forage for cattle. It is often used for roadside erosion control, as well as beautification; it tends, however, to eliminate all other desirable spring and early-summer species of native vegetation in the area where it is planted.
In Cesar Chavez Park, however, this clover stands little chance of taking over the lot, as the land teems with other ruderals just as invasive and aggressive.