Oxalyldiaminopropionic acid (ODAP) is a neurotoxin that causes the neurological syndrome called lathyrism. Can be found in seeds of Lathyrus sativus (grass pea)
Picture 1: L. sativus plant and seeds
L. sativus ia a leguminose plant which can be found in the mediterranen area and some regions of Asia and Africa. The seeds of this plant have a big amount of ODAP, which is toxic for humans and other animals.  The aminoacid β-N-Oxalyl-L-α,β-Diaminopropionic acid is an structural analogue of the neurotransmitter glutamate. ODAP causes a motor neuron degenerative disease which results in paralysis of the lower body. There is a degeneration of pyramidal-tract neurons in the spinal cord and in the area of the cortex controlling the legs, due to its resemblance with glutamate. ODAP also causes spastic paralysis of the lower limbs, spinal hyperreflexia and structural changes of skeletal connective tissues. This also results in deformities. 
Intoxication nowadays is rare, because it is needed a very frequent consumption (almost exclusive) of grass pea seeds. However, the rate of latyrism has happened historically in times of hunger – when no other aliment was available - such as post-war times or famines.  The painting “Gracias a la almorta” by Francisco de Goya represents people suffering from latyrism due to a very high consumption of the seeds after the Spanish independence war (1808-14).
Picture 2: “Gracias a la almorta”, Francisco de Goya
In the region where I am from in Spain, Castilla La Mancha, there is a traditional dish based on flour from those seeds, Gachas manchegas. Human consumption was abolished in Spain in 1967 but the decision was revoked in 2018 by the Spanish Agency for Food Consumption and Safety (AECOSAN) and hence, a rise in its production is expected.
Picture 3: Preparation of “Gachas manchegas”
Structure from PubChem
 “The Isolation and Characterization of β-N-Oxalyl-L-α,β-Diaminopropionic Acid: A Neurotoxin from the Seeds of Lathyrus sativus* | Biochemistry.” [Online]. Available: https://pubs.acs.org/doi/abs/10.1021/bi00891a022. [Accessed: 20-Dec-2019].
 “Neurolathyrism: two Ethiopian case reports and review of the literature | SpringerLink.” [Online]. Available: https://link.springer.com/article/10.1007%2Fs00415-011-6306-4. [Accessed: 20-Dec-2019].
 “Lessons from neurolathyrism: A disease of the past & the future of Lathyrus sativus (Khesari dal).” [Online]. Available: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3767245/. [Accessed: 20-Dec-2019].
- From https://en.wikipedia.org/wiki/Lathyrus_sativus. Creative Commons Attribution-Share Alike 3.0 Unported. Author: Arr4 (talk)
- From https://www.123rf.com/photo_10527109_fresh-lathyrus-sativus.html Author: Mohammed Anwarul Kabir Choudhury
- Francisco de Goya (1811 - 1813). Gracias a la almorta [Painting]. London, British Museum. From https://research.britishmuseum.org/research/collection_online/collection_object_details.aspx?objectId=1335061&partId=1
- From https://www.eldiario.es/consumoclaro/por_derecho/Harina-almorta-producto-prohibido-trampa_0_816819224.html