A downhole valve includes a housing, and a sleeve positioned within the housing. The sleeve has a first axial end, a second axial end, and a seat positioned between the first and second ends. The sleeve defines an opening facing in a radial direction. The sleeve prevents fluid flow in an opposite radial direction, away from the opening. The valve also includes a retaining element coupled to or integral with the sleeve, and a first obstructing member positioned in the sleeve and movable between the seat and the retaining element. In a first position, the first obstructing member engages the seat and prevents fluid flow through the housing. In a second position, the first obstructing member is separated apart from the seat such that at least a portion of the opening is axially between the first obstructing member and the first obstructing member.