The first one seems a Euphorbiaceae plant. It is Euphorbia sp. Please find attached herewith some useful resources on the flora of Barak valley of Assam.
Yes, I agree with Dr Singh. The first plant is Euphorbia sp (Euphorbiaceae). The second plant from the shape of the flower is Fabaceae (Papilionoideae), and very close to Indigofera. Also check the materials provided by Dr. Singh for Indigofera and related spp.
The second plant is a small herb I got it only one time in my field in the month of March April but I am unable to identify.I thought it to be under family Fabaceae or Linderniaceae.
The first plant seems close to Euphorbia thymifolia /Euphorbia hypericifolia. It also resembles Euphorbia maculata but I suspect that the latter species is found in Assam.