Common Vetch
Vicia sativa
Family: Fabaceae (Pea)
Flowers — color: magenta, size: 1/2", type: pea, banner & keel

Common Vetch has a pea flower [banner, wing, and keel petals, see 'Pacific Pea']. The colors are purple or magenta. Pairs of blooms attach at a leaf stem node.

Vetch flower leaf Vetch and white horkelia flowers wider view photo #1 growing tip of this stem trimmed by deer

Habit:
Common Vetch is an annual. A vertical stem holds alternating leaves. Each compound leaf is pinnate: alternating pairs of leaflets and may reach six inches long. They end with several tendrils that can grasp neighboring vegetation for support. Each leaflet is a smooth, narrow oblong ending with a short spine. Non-native, sometimes a weed, sometimes for restoration. Open sun.